UV1 as above but without the timer. Supplied with extensive applications software. Please phone for details. A ready built totally self contained speech synthesiser unit, attractively packaged with built-in speaker, AUX output socket etc — no installation problems! It allows the creation of any English word, with both ease and very can easily programs vocabulary, whole applications commercial, recreational etc no need plugs into due to the simplicity, while, at the same time being economical in memory usage.
You add speech to most existing Due to its remarkable infinite its uses spread throughout the spectrum of computer — these include industrial, educational, scientific, No specialist installation — to open your computer, simply the the user port — and -- simple software, no ROMS are needed. BUZZBOX This is a full specification, direct connect modem, with both Originate and Answer modes, allowing access to the many databases, bulletin boards, as well as inter- computer communications.
Having full BT Approval, it connects directly to the telephone line, for optimum performance. Being battery powered, it is totally portable optional power supply available. Please add carriage as indicated and add l5 v o VAT to the total order value. Records consist of a number of FIELDS containing the information— an analogy can be drawn with a card index in which a box of cards is the file. Each card is a record and each line on the card is a field.
When you buy disk drives you do not have to throw away expensive cassette based programs. No waiting for 6 minutes whilst adventure programs load. Press play and let the program do the rest, even a menu. The original disk utility program for the BBC that provides the user with the tools to explore the disk environment and use it to its best advantage. More fun than any adventure game. Every disk owner should have one.
Converts non joystick programs to work with joysticks. The routine is relocatable and sensitivity of the joystick can be varied. Compatible with most games, including Acornsoft. Very easy to use, just press the keys you want to transfer. The machine code can be saved as a block of just bytes. Supplied on cassette but can be transferred to disk. This allows you to view all areas of memory, search and alter bytes, etc. Colour coding helps to simplify memory usage.
Green screen 18 MHZ H. Green Monitor Phoenix High Res 1? Econet interface - In short it is a personal computer capable of expanding into a small business syslem. Speech interface bee lilting! Back in the thirties there were almost as many radio magazines as there are computer magazines now. Today modern receiver design has packed the power of those gigantic World War Two radios you used to be able to get in government surplus stores into a tiny compact portable. Modern short-wave radios are small and powerful.
Even the minuscule Sony 1c is a full-facility receiver with the kind of pulling power that brings in stations from all over the world. When you listen to one of these sets you'll hear mixed up with the hundreds of foreign voices a strange collection of dots, dashes and chirping sounds. It is these normally unintelligible signals that are potentially the most interesting and, using a BBC micro, you can begin to unscramble some of them. The big question is, why bother with all these special codes when it is easy these days to talk over the radio?
The trouble is that transmitting voice - radio telephony - uses up a lot of radio space, and there is only a limited amount. Transmitting messages by radio telegraphy and radio teletype makes more efficient use of the radio frequencies and over long distances is more reliable. Often interference makes voice reception very difficult whereas telegraphic and teletype sig- nals can still be decoded successfully.
Because of this, those blips, blops and chirping noises often carry very interesting messages. Before looking at how to receive and decode these messages a pause for some history and explanation. Radio telegraphy started in when Gug- lielmo Marconi transmitted the first transatlantic radio signal. He used a dot-and-dash code invented earlier by Samuel Finlay Morse. In the Morse code each letter and number is repre- sented by a series of dots and dashes: Soon people wanted to transmit messages faster and use machines for automatic sending and receiving.
The asynchronous Baudot code baud is most commonly used today. This is made up of five data units repre- senting alphabetic information, and because the receiver is not synchro- nised with the transmitter a start and stop unit are added. Each of the five data units can have a value of 1 or 0. RTTY signals are normally transmitted at a number of different speeds. These are 45, 50, 57, 75, and baud. So what do you need to turn these codes into something readable? The first thing apart from a BBC micro is a short-wave radio.
All the new generation sets have this facility. The Icom 1C R70 is one of the top- range sets. Both are full-facilities short-wave radios and offer good reception on the FM band for ordinary radio programmes as well. Next is an aerial. The two portables come with telescopic aerials but these aren't good enough to pull in the really distant stations. The simplest kind is a long piece of wire the longer the better , either stretched from a con- venient window to a nearby support or hung down the side of the house. A really neat indoor one is the Datong Active Receiving Antenna. Both include their own power supply.
Then comes the all-important link between the radio and the computer: When you tune into an RTTY signal it is unmistakable - it really does sound like continuous chirping. This is because the signal is made up of two tones rapidly switching from one to the other. The lower tone represents the space, logic 0, and the higher the mark, logic 1.
The dif- ference between the two frequencies is usually quite small on the ordinary high-frequency HF short-wave band that is, between and 30, KHz. The two frequencies are 85 and Hertz. On the FM band they are 30 and Hertz. The decoder changes these two tones into zero volts and five volts respectively to represent the two logic levels of the code and feeds them into the user port of the micro. Again, a glance through the radio magazines shows a number of small firms making decoders for most of the popular micros and they supply the necessary software to work with them. These flicker on and off in rhythm with the signal, when it is tuned in properly.
The LEDs are really important because as you turn the radio tuning knob the pitch of the sig- nals varies quite dramatically and you have no way of knowing when it is right. Turn the knob until the lights start puls- ing and then you know logic signals are being sentto the computer. All it has to do is detect the start and stop bits of each word, refer to a look-up table to find out what character the five data bits represent and then print it on the screen.
It has to do this quickly, of course. The documentation is clear and easy to use. It allows you to select a baud rate of 45, 75 or and offers the facility for driving an Epson printer. When every- thing is tuned in and set properly words suddenly appear on the screen, a very exciting moment. If gobbledegook starts to appear try changing the baud rate before assuming you are receiving a coded message.
Uniden CR communications receiverfrom: Datong Active Receiving Antennas from: RTTY computer interface from: You may experience interference problems from the computer itself, for the BBC micro transmits a lot of radio frequency signals. Make sure the aerial is as far away from the computer as possible.
When the foil shield is connected to the ground it stops the interference signals from escaping. Sometimes you may not be able to resolve a signal into words at all. This could just be because it is being trans- mitted at a non-standard baud rate or frequency shift, or it could be that it is on one of the newer Teletype systems. There are two main contenders to the Baudot code: There are two types: In both each data word has a checksum included so that the receiv- ing equipment can tell if an error has crept into the transmission.
These books list the frequencies of most of the agencies in the world using RTTY that if an error has been detected the receiving station transmits a signal to the sender asking for the last character to be transmitted. This is quite complex and requires the user to have a trans- mitter and a receiver. Use of a printer is optional. Write to or telephone Gemini for further information, or complete the coupon — As well as tuning in to most of the satellites and to RTTY, it of course receives domestic radio broadcasts.
The RSGB administers and governs all the amateur radio clubs so is a good source of information about becoming a radio ham. It receives long and medium wave and VHF broadcasts as well as short-wave. The frequencies on which ama- teur radio transmissions may be received. They cover European, Russian and African transmissions character. You are allowed to receive the amateur transmissions and these can be found on the bands listed in figure 2. The three books illus- trated in figure 1 give the names and frequencies of most of the agencies in the world using RTTY so: And remember 3" disc drives are fast becoming the standard for home and business use.
This is an even bigger bargain than it sounds. It reads and writes to the disc cartridge from both sides, giving you twice the on-line capability of other 3" drives. Smith John Menzies and leading specialist shops. Please rash me the following: I Op as Supplies L td. The programming task you set about will depend on your own inclination: Whatever target is chosen, all pro- grams will, surprisingly, follow essen- tially the same general rules.
In fact, almost every program you write will in verbal terms look a little like this: Set all variables Set up screen Print information Get information Update items If finished end If not finished start again As you can see from this list the rules are very general, but they provide a sound basis to expand from. The order might vary. For example, you might wish to set up the screen display before setting up variables or get information before printing any information to the screen, and soon.
The list above, though very general, is an example of structured programming: The program is simple, but provides easy animation and sound and can be stopped at any time just by hitting the space bar. The idea is that we get a fly to buzz to and fro across the top of the screen and when the space bar is pressed it crashes to the floor with a thud! Before starting we need to think about our requirements. Most obvi- ously we need the fly. The easiest way to provide animation is to use the PRINT statement to put the asterisk on the screen, rub it out and then print it in the next location along the screen, thus pro- viding the illusion of move- ment.
To make this easier a special print positioning command is available in BBC Basic. This is the TAB short for tabulation command. TAB treats the screen like a sheet of squared paper divided into rows and columns, the first column and first row being at the top left hand corner of the screen. In computer terms this is referred to as column 0, row 0 rather than column 1, row 1. Instead of using the long-winded column and row refer- ences these numbers are placed in brackets.
For example, to print an asterisk at column 5, row 2 figure 1 overleaf we would use: The actual number of. Here we have introduced a variable to keep count of the column, and to remind us of that fact I have called this variable column. The term variable implies its use, and it is really just a counter with a name. The count vari- able is used as one of the two values inside the TAB command.
The row count remains constant at 3 so that the asterisks are printed side-by-side across the screen. Rubbing out each asterisk is performed in a similar manner and within the same loop. All that needs to be done is to print a space over the old asterisk. Add the following lines: Line 34 prints the space that blots out the asterisk. Note as in line 30 above the use of the two semi-colons after the TAB command. These simply ensure that the computer keeps print- ing on the same line. Try playing around with loop values to see the effect of different values the best way to learn computing is to experiment!
So far the fly just moves from left to right across the screen. To move from right to left, all we need do is get the printing loop to count down from 79 to 0. A fly tends to buzz, so some experi- mentation with the SOUND command should provide the right sort of noise. To get a continual buzz try placing this in a suitable position in the FOR. Selective printing any number of labels, repeat, stationery or fan fold.
TR 14 OJX tel: To do this we need to incorporate a keyboard test or scanning routine. Two lines are needed for this as follows: String variables of this kind are used to hold a character a keyboard character in this case as opposed to a number. At the start of the article I laid out a general program instruction list and talked about structured programming. Writing it down on paper we might end up with: Set up MODE 0 screen 2. Set up move fly left to right loop 3.
Do fly moving procedure 4. Set up move fly right to left loop 5. Do fly moving procedure 6. Repeat items 2, 3, 4 and 5 until fly is dead Now we have the main program, albeit in words, needed to perform the task in hand. In fact, these items are minor and are considered as subsections of the main program.
Consider item 2, the fly- moving procedure. This could be sub- divided as follows: If space key tested then do die pro- cedure c. Make buzz sound d. Do a delay loop e. Do items a,b,c,d, and e until com- plete This list of items compares to the short lines of program we developed above. BBC Basic is unique in that groups of statements can be enclosed inside a special program casing called a pro- cedure that can be given a name and placed outside the main program. A typical program containing a pro- cedure might go like this: The pro- cedure itself is prefixed by a special command DEF, which is shorthand for define.
We need to incorporate another pro- cedure in the program that will be exe- cuted if the space bar is detected being pressed.
Welcome to Reddit,
PROCdie might be written like this: We know exactly what our program needs to do and how it per- forms it without so much as writing a single Basic command, apart from a bit of early experimentation. Get into the habit of doing things this way; it may seem long-winded at first, but I can assure you virtually all professional programmers write their programs in this way.
Finally, the program listing 1. Look carefully at it, trying to pick out the structure within it and how the com- mands relate to the list we constructed earlier. You might not recognise several of the commands so get your User Guide out and find out exactly what they do. If you are still not sure try experimenting with them to see the effects that different values have. Pro- gramming is all about practice and experimentation. As you design the sprites they are automatically stored in our sprite routine which lies hidden under your program.
The machine code sprite routine will move the shapes at incredible speeds of fourteen 14 times that of ordinary basic - and the routine is controlled with simple commands from your own Basic program! Simonsoft sprites are used in programs on the market now. We claim no royalties on programs using our sprite routines. OG is in a calamity. His territory has been taken over by dinosaurs that lay eggs at a really hectic rate. Og must crush the brood before they hatch by jumping on to each and every egg.
Og's problems are compounded by a pack of slavering dinosaurs hungry for his blood - and on higher levels by grand old Ma dinosaur herself. Og can use his magic staff to set a trap, but time is precious as Og knows all too well. Big bonuses can be scored for jumping on fruit, and an even bigger bonus for snatching a kiss from his waiting cavewife.
Supergamble for the jackpot and a coin pile that shrinks and grows with your winnings. Separate instruction pro- gram. This implementation is in a class of its own. Hidden under your Basic program the routine need take as little as 1. I wanted to give the user a non- stop game in which he would have to have his wits about him all the time so as not to lose interest. The game starts off with three Para- noids Paras for short coming down from the top of the screen and you have to shoot them with your laser-powered tank before you pass on to the next level.
If a Para lands before you can shoot him you will lose a life, and the game is over when you lose three lives, and your final score will be displayed. The game is played on just three keys. Left and right movement of the tank is controlled by the Z and X keys respectively. The game was written on an Electron but it is compat- ible with the Beeb. I started the project by drawing up a flow-chart figure 1. This is an essential part of design- ing a program, as it sets out the whole structure. My next step was to construct a vari- ables table figure 2.
As you can see, all the names mean something to the program- mer and are built up in such a way as to remind him what he is doing -thus cutting down on debugging the program. Next I wrote down the program on coding paper, which is divided into rows and columns, one character per block. The point here is that it helps speed the completion of the program. This is how the program is struc- tured, with a breakdown of the pro- cedures: This procedure also defines whether the Para will come straight down, from the left or from the right.
When the X key is pressed it ceases to continue. This procedure also checks if the left or right key has been pressed; if either has then it is acted upon and produces a sound. The Paras can only move between columns 3 and 35 of the screen; if they move outside these limits they reappear on the other side of the screen. So if a Para reaches column 35, its X position is made equal to 3 and it reappears on the left-hand side. If it has a sound is pro- duced and the laser is drawn. This then prints an explosion over the Para, a delay occurs and a space is printed over the Para and a sound produced.
This means that the Para is stored as TAB 3,2. At this point the laser from the tank is unable to reach across this far, so giving the impression that the Para is no longer there. Normal, Italic and Elite Graphics. Tractor feed, 10" max width, bi-directional, logic seeking. Securicor [ As above but has both Friction and Tractor Feed.
Normal, Italic and Elite characters. Up to user definable characters. Down loadable character set. Condensed and double width printing. Four user defined margin positions. Tractor and Friction feed. Prints in two colours; super and subscript facility. Impact control facility to vary pressure on paper for making carbon copies. Has Centronics parallel or RS interface. Connects directly to BBC Micro.
A ribbon cassette plus a separate red ribbon. Attractively finished in beige. A 4 way mains distribution socket. I Manuals and all the leads. To enable you to carry I your Micro around, we shall pack it in our Antique Brown leatherette Attache carrying case. We will alter the package to suit your requirement. Call in for a demonstration. Single sheet feed and built-in Paper Roll Holder. Dot addressable graphics 8, 9 and 16 pin modes. Half speed quiet mode, Convenient Paper-out sensor switch. All this plus our no quibble 12 months warranty. Will accept upto 17" maximum width paper.
Our Programmer has been designed to make sure the EPROMs are neither programmed too fast nor too slow; just at the right speed as recommended by the manufacturers of the EPROMs any deviation in timings can burn their brains out. Just look at these features: Rushing it could burn their brains out.
So cop-out of this helter-skelter world; take it easy the TEX way and give your chips a well earned break. Cool, gentle and affordable. Has an incorporated safety switch which automatically switches off the UV lamp when the Eraser is opened. Stores, protects and displays 20 discs in double-sided clear view pockets.
Supplied with adhesive title strips for ease of filing. Very simple to use. Track density 96 TPI. They are fast, efficient and highly reliable. The length of your files is restricted only by the space on your disc. You can have upto 20 fields with page length records of upto characters. The program is completely menu driven obviating reference to a manual although written guidance is given with the program. Add and delete records, amend title, field names and records, sort on any field and search for any record or group of records in any field You do not need to abandon or rewrite your files if you wish to add additional fields or extend the length of any field, the program will rewrite the files for you.
Your files can be in any drive Output can be in Two forms of output are provided for horizontal for label type output and a tabulated output with title and Headings What is more, the selected fields can be placed in any order on the screen In the horizontal mode you can scan backwards or forwards with wrap around effect. Output can be started or stopped anywhere in the file. There is automatic totalling on decimal fields and an automatic count of the number of records output. Now with extra 3 features: A database may occupy your total on-line storage capacity. You may design any number of data entry forms using a "paint'' on screen technique Forms may be upto 3 screens in size.
A form may be used to Add Delete. Print and Spool records from your Database Quick search facility on any text field A query language provides full maths support -. I when used with the keywords - Assign, Compare. Read, Search, Spool and Update Full printed output control via embeded commands.
Supplied with 70 page manual and fitting instructions. An ideal ROM for engineers, programmers, teachers, students, etc. User defined Graphics and line drawings for video titles. You no longer have to throw away any of your cassette based software on acquiring a disc drive. It handles locked programs and allows you to load full length adventure type programs i.
It is very simple to operate full instructions supplied. It saves you your valuable time and money too. A must for all the Assembly Language Programmers. It has all the normal memory editing, moving and relocating facilities, plus all editing is with a full screen editor allowing scrolling up and down memory, entering in Hex, ASCII or standard assembler mnemonics.
theranchhands.com: Peter D. Slade: Books
In use as a debugging tool, you run code under a total emulation system. Everfelt a desperate urge to set a break point in ROM? No problem - you can even have breakpoint on reading or writing locations in memory and on register contents. The system fully supports debugging of sideways ROMs e g.
Beebmon can even run itself. In so doing you can nest Beebmon up to a level limited only by the memory size. Beebmon uses bytes of workspace, located anywhere in memory, even on the 1MHz Bus. Beebmon effectively uses no zero page workspace, so your program e. BASIC can use any or all of the base page. How does it achieve this? By providing a interpreter all programs running under it exist in a vertual BBC. Emulation also allows immediate return to Beebmon command level by ctrl-escape no matter what code is being excuted at the time.
All this exceptional power and flexibility is complemented by a clear and detailed manual included in a value for money price of: Disassembler Rom 3 6 0. There is also a full set of labelling facilities available up to 3, labels , with the major locations and routines already labelled. It has all the features of a professional word processor yet is easy to use. Put the precious originals away in the safe and use your duplicates. See what your can do 1 With Watford s Investigator you can find out about track formatting, sector length, etc. Investigate your disc and then make up your back-up copy.
Disc based software includes a comprehensive manual. It allows you free hand drawing in all colours. Has Special effects facility and many educational uses. An ideal and easy way of communicating with Micros for Children. This compact board which fits inside the computer does not just give you 16K or even 20K of extra RAM. There are many useful facilities available with this board: This allows good graphics and long programs to be combined. It helps you to create your own application programs by the simple use of the Graphpad Ideal for Educational use Supplied complete with Cables.
Manual and a two program cassette Price: Simply replace your standard 13Amp mains plug with the surge protection plug which is almost the same size. Hi-Fi systems, precision instruments, fridge freezers, etc. A must for all serious computer users. There are only 5 solder connections to be made. Full instructions are supplied. This board has been ergonomically designed to enable the user, easy further expansion inside the Micro, e. Double Density Board, Torch Board, etc. At Watford, we think ahead. In addition the board is designed with the facility to hold upto 16K RAM. This gives the User the ability to write a utility or language and upon pressing break have the utility or language up and running new ROM software can be developed and tested in situ.
The Board gives the User, plenty of freedom to explore the possibilities of the new paged ROMs due in the coming months and offers them the chance to develop their own All lines are fully buffered and the Board meets or exceeds all timings for operation in the BBC Microcomputer.
When fully populated the ROM Board consumes less than half the recommended maximum current limit. Complete with easy-to-follow manual. No extra speech dictionary chips to buy! Auxiliary output socket provided for direct connection to an external , amplifier.
Educational Programs, Specialised Packages. We know this all seems to good to be true but! Order your Versatile Speech Unit now! The system consists of a mother board which fits inside the BBC and further daughter cards can be connected externally. Any RAM is Automatically battery backed-up and it's contents preserved when the power is turned off. There is no soldering required. The board is rigidly held by two 40 pin sockets and five support posts. A ribbon cable can be brought outside the computer and up to 8 external cards added. This enables the user to plug-in up to paged ROMs.
The cards have following features: The system comes with controlling software in ROM. The utilities supplied are as follows: ROMs present and files stored. This also reports on the amount of free storage space. This will write a test pattern into the memory and read it back out again. If a fault is found, it is reported to the user. This test continues until Escape is pressed. All commands have similar format to the DFS and transfer is possible between the two systems. By racking the cards you eliminate the tangled mass of cables that usually accumulates around the micro.
Please write in for further details and prices. Once fitted, the 16K ROM will enable you to produce attractive text displays in following different styles: What do the independent press say? Good value for money - Beebug Aug. It consists of over 14K of efficiently written machine code.
It is entirely self contained and so does not require a utilities disc to function. Please write in for full technical specification. We do NOT retail through any dealers. Need sensible paging for use in the creation of booklets? Up to 30 come pre defined, without effecting normal fn key usage. Puts gaps in listings. PRINTed text etc to skip the folds. The gap size alternates to minimise paper wastage when using binders. Can also provide a left margin.
Operates with Parallel and Serial Printers. Supplied complete with a comprehensive 50 page manual. These are both 2 byte numbers giving you very fine control over the dump size from minute to enormous Unlike other dump Roms, scale does not vary with screen mode. The area of the screen dumped is that in the graphics window, alternatively these parameters may be given.
Otherwise use a negative scale, i. Prestel gives you access to an incomparable database covering almost every subject under the Sun. There is Micronet with lots of free programs that you can download and run. Details of Clubs and User groups, a diary of meetings and exhibitions, news and reviews, technical information, etc.
There is Homelink with On-line banking. Business News, Weather information, Electronic mail and lots more. Can you afford not to be part of this revolution? Now using the latest techniques and the new generation of Modem chips, Watford have developed a Modem that is newer, better and yet cheaper than any on the market. French or German Characters? The disc contains an example as well shows how to use. Available on 40 or 80 track Disc. Disc and Tape configurations fully supported. An overlay is provided giving simple yet comprehensive guidance to the key functions.
Order and Application Forms. It has all the features of the single density DFS. Allows single files upto K. It will automatically tell whether a single or double density disc is being accessed, as well as allowing the option of reading 40 track disc on an 80 track drive. Delivery 4 weeks approx. An ideal and very safe way to carry your BBC Microcomputer. This sturdy plinth is attractively finished in BBC colour. Air vent slots have been provided to allow maximum air circulation.
It can be used to support a monitor or a printer. The micro slides underneath comfortably. Place the printer on the plinth and the paper underneath. Finished in BBC colour. Ideal for Micro Computer and peripherals application. Prevents you getting a dangerous tangle of plugs and adapters. Unless stated otherwise, please add 75p to all cash orders. Move one space in front of the target so that, if the Para is coming down from the right, you pos- ition yourself one space to the left and keep your finger on the fire button.
This means that it will have to go through the loop 16 times before it registers. You might find this frustrating but it adds to the fun of the game and would be too easy if it registered as soon as the laser hit the Para. Current X co-ordinate of tank. Theactual calculated laser position. The explosion used when a Para tankS has been hit. The character used for the tank. The rest of our range of titles for the BBC Micro except Filer and Draw will also be available on disk but without the colour packaging.
Perfect Speller, Perfect Filer and Perfect Calc, plus 12 months on site warranty monitor available at extra cost. Mailmerge, Info-Star and Calc-Star. Includes free tape recorder. Full range of Software and Disk Drives available. Call for our full price list. Diskettes Memorex, in packs of 10 SS40tk. It is extremely useful allowing vast amounts of information to be quickly stored.
Once set up, the information may be retrieved or sorted at any time, in a number of different ways usinq any of the fields as keys. Records may be instantly displayed or printed, using any printer suitable for the BBC Micro, also a label printing facility is included. Separate versions of the program are available for cassette and disc based systems. The disc version uses random access files to maximise record storage. One extra feature of the disc version is that it provides limited spreadsheet facilities.
It provides an automatic spelling check for letters or documents. It is supplied with a dictionary disc already containing words, which may be increased to a maximum of about 17, words on a k disc. Random access files ensure very fast word retrieval from the dictionary disc.
- Afghans pour le crochet (French Edition)!
- Cognitive-Behavioural Interventions with Psychotic Disorders;
- Sensory Deception: Scientific Analysis of Hallucinations.
- Friedrich Dürrenmatts Theaterstücke. Erläuterungen zu Die Physiker und Der Besuch der alten Dame (German Edition)?
- Le Baiser du rasoir: Basse-Fosse, T1 (Fantasy) (French Edition).
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Incorrectly spelt words may be instantly respelt and a correct version of the document filed away, ready for printing or later use. Dictionary discs for foreign languages may easily be created to help check letters sent abroad. Any number of files may be set up, and each file may hold about records based on a typical 5 field record. The disc version allows up to 1 7 fields per record, and the only limitation as to the number of records, is the capacity of the disc. Typically, using 5 fields, about records may be stored on a k disc. Works well and offers an efficient data base It will then auto- matically enter the Screen Editor display the line in error and position the cursor close to the statement at fault.
The range is enormous an indispensable aid packed full of powerful utilities. Since it has been installed in my BBC it has been used extensively and I can find no fault with it. Highly recommended to lazy programmers! Available from your dealer and selected branches of W. This will stop the computer listing a whole program without stopping. The computer stops when about two-thirds of the screen is full of information, and the next part of the listing will only appear when the SHIFT key is pressed.
However, when checking a long list- ing, page mode is not the complete answer. Paul Holgate has sent a useful function key definition program listing 1 that allows the user to step through a program a few lines at a time. When function key fO is pressed, a list com- mand is inserted into the function key buffer and the screen cleared. It will list a group of lines in multiples of 10 from 0 to 9 each time key fO is pressed.
To enable any starting point to be used for listing, key fl has been defined to input the start point from where the listing is to run. Key fl must be used before attempting to step through a listing. The usual start point will be at line 10, although listings can start at line 0. There are cases where opening brackets are actually part of the Basic keyword.
With such keywords, the inclusion of brack- ets is essential. Also there must be no space between the keyword and the bracket. The following keywords require brackets: It oc- The ideal method for card games. BBC Basic has quite a useful range of string-handling routines, many of which are underused. Listing 2 shows my method. It is shorter than the Beeb Forum listing, which for the sake of completeness is repeated listing 3.
To my surprise, it is also on average 10 times as fast! Speed of performance was rather difficult to measure, as each run varied consider- ably depending on the luck of the draw. I therefore ran each routine times to find the total time taken. Listing 4 is included to show the idea for those interested. This way of selecting a random sequence would be ideal in card games, as it is easy to include the jack, queen and king. Listing 5 shows how this could be done. Notice that in line 80 the test to see if the number is already present includes the following space.
This overcomes a problem that the test does not recognise the actual number but just a digit. In this example we need to include a The test as it stands in listing 2 will see a 1 present when it is meant to be a The inclusion of the following space in the test prevents this from happen- ing. Listing 6 shows how the technique can then be extended to a full pack of cards.
Surprisingly, it takes only some seconds to select a full pack. I hope these short programs will make readers take another look at strings and their possible uses, and maybe those who discover novel string applications will be prompted to send them in. Consider the following line from a program: It can be made more readable by using a print statement: There must be an advantage to using the former method- memory perhaps.
The first line of code took 34 bytes of memory, the second 28 bytes and the third only VDU commands have their rightful place in programming, but use them with care and ensure they do not hinder understanding of the program. The problem was first highlighted in this column in December It is a problem that can affect many program applications, and many new readers have joined Acorn User since last year, so I make no apologies for repeating the point.
How do the BBC and the Electron handle numbers? Well, they differen- tiate between two types of numbers: They can store only numbers between -2,,, and 2,,, Integer variables are stored with complete accuracy and are operated on more speedily by the computer. This enables values to be carried by these variables from one program to another. Real numbers with a value between 2 x 10 38 and 2 x 10 39 can be stored by the computer and can include negative numbers. The disadvantage with real numbers is that they can be stored only to nine-figure accuracy.
Basic 2, the version of Basic present on the Elec- tron and new BBCs, will work to a figure accuracy. The numbers must be converted to binary before being stored and this leads to many problems. Some numbers cannot be represented with complete accuracy this way. This is a similar problem to the recurring deci- mal found when 10 is divided by 3 or when trying to calculate exactly the. This ratio, called pi, is a never-ending decimal, and can never be represented with total accuracy.
To illustrate the difficulty of storing and retrieving numbers accurately look at listings 7 to 9. Listing 7 works as one would expect, but with only a slight change in numbers listing 8 does not give the correct result. It is interesting to print out the values for A, B and C and see what happens to them. Listing 9 will do this, To add to the confusion, we find that it prints out the correct values even though the program has given the wrong result! Before you throw your computer away and rush out to buy another make I should point out that this program will not function correctly on the majority of other micros.
The reason is that the computer has a routine built into the PRINT statement to check for the correct errors in number storage and retrieval. Unfortunately there are no such routines in the equals, greater than or less than operators and these give rise to problems, particularly when trying to perform money calcula- tions.
There are two possible ways round the problem. The first is to multiply the real numbers by and work in integer arithmetic. To display the results divide them by For the sake of simplicity we are assuming that half- pence will be ignored. Listing 10 gives an illustration of this method. By using integer arithmetic it is poss- ible to store values up to 2 million pounds accurate to the nearest penny. This method as it stands is not fool- proof, as real numbers still have to be stored in memory. To get around this, instead of multiplying and dividing by , change the program to multiply and divide by This means that the real number is converted with a ten-fold greater accuracy.
It now also enables half- pence to be entered. The other cure is to use a relative test rather than trying to equate two totals exactly. Listing 11 shows how this can be done. The ABS statement ensures that the test will work if either total is larger. Disc detector ON A BBC machine fitted with disc interface it is often useful to detect the presence of a disc drive during a pro- gram, say to give the option to save data on either disc or cassette.
A way to do this is to assume that if a disc drive is fitted then the program will have been loaded from disc. It will give an error message with a disc filing system, but not with the cassette filing system. It gives error number bad option with disc. This could be detected to differen- tiate between tape or disc, or the line number at which the error occurred can be detected as in listing To check that listing 12 will work on a disc machine of course type RUN, then press BREAK, which will rerun the pro- gram but with tape option selected. Printer check SOME programs that make use of a printer tend to hang up if no printer is present.
It is better to include a routine in these pro- grams that checks to see if a printer is connected first. The ADVAL statement can be used to check whether a printer is connected and switched on, and a little-known use for the statement is to check the state of the various buffers. ADVAL -4 will check the state of the print buffer.
Listing 13 shows the technique. If it is, a value of 63 will be returned. If the space is held in the buf- fer then the value returned will be This idea is easy to incorporate into programs. Ribbon rewind HERE is a tip that will double the life of some printer ribbons. When the printing is becoming faint and a new ribbon is needed, try opening the cartridge and removing the ribbon. Re- place the ribbon upside down and re- wind the ribbon back into the cartridge.
This trick works because many printers do not print in the middle of the ribbon, but near one edge, so reversing the ribbon allows the other edge to be used. Some cartridges are better designed, however, and the ribbon already has a half twist in it so that the top and bottom of the ribbon are both used - in which case this tip is no use! The flagship ABC certainly lives up to its promise, for It has been demonstrated running a sophisticated, mouse-controlled desk-top manager with icons, menus and windows. For those of you who are baffled by such jargon, it provides a software simulation of a desk complete with overlapping sheets of paper windows , disc storage shown as pictures that are known as icons and possible things to do presented in menus.
The success of the machine, as with any business computer, will depend to a large extent on the amount of appli- cations software written for it. On this front Acorn has certainly hedged its bets with all the popular operating systems available, and response at PCW was good, said Howard Fisher who is responsible for the ABCs. Beneath the monitor screen on the left is the Winchester hard disc, with the floppy drive beside it. Note the new symbols on the keyboard, re-arranged function keys, keypad and the mouse.
There is no break key, but a reset is fitted on the rear of the keyboard. I I The hard disc has been accessed here hence the icon in black on the background to display file C: Two win- dows showing parts of the 12 files in C: Computer output to the printer is stored in the buffer so that the computer can continue with other tasks while the printer works from the stored contents in the buffer.
Daisy-wheel quality gives a professional look to your correspondence. Facilities include 18CPS, bi-directional print, 3K Buffer with clear facility, carriage skip movement, text copy switch, proportional spacing, underlining, bold, shadow, super and sub-script, printing in two colours. Impact control allows use of carbon paper. Connects directly to the BBC micro with centronics parallel interface. RS interface is an optional extra. Other options are a single sheet feeder that automatically feeds up to 1 50 single A4 sheets and a keyboard to transform the printer into a sophisticated electronic typewriter.
RSC Interface, tractor feed attachment, single sheet feeder. It is solidly built and features include: Extras over the FX80 included in the price are Near Letter Quality NLQ print ideal for correspondence, properadjustible tractor feed, half speed quiet mode and 3K buffer. The printer is bi directional and logic seeking to give a speed of CPS for high throughput in conjunction with the standard 3K buffer.
Gives 1 56 columns of normal print or columns in condensed mode. Worried about compatibility with single density discs? Other manufacturers thought that read and write sector alone were sufficient - we decided to implement every command of the that was physically possible. We have allowed the use of all the special registers including bad tracks, allowed access to deleted data etc. The emulator itself takes up around 1 K of compactly written machine code. We reckon it will run the vast majority of protected discs now available.
Gain all the advantages of the WE DFS together with much increased storage and compatibility with existing protected discs. The price is the same as for the standard single density system that we continue to sell so you can choose between the two options without financial worries. Double sided 40 track. These discs are quiet in operation and insert positively with their reinforced hub rings.
Boxes of 10 supplied with disk labels and write protect tabs. Each disc can easily be seen through the clear view pockets. The' smoked top locks down. Dividers and adhesive title strips are supplied for efficient filing of discs. Drive manufacturers recommend that you clean the heads approximately once a week. Unless your home or office is dust free one of these kits is a very sensible precaution against losing valuable data. A dirty head can destroy many disks before you realise the trouble. Very simple to use. We supply everything you need to get a BBC micro running as a word-processor.
Please call in for a demonstration. Twin k Teac drives in beige. Zenith 12" Hi-resolution monitor Green or Amber. Brother HR 15 daisywheel printer. Choice of a monitor is a matter of personal taste so we recommend that whenever possible, you ask for a demonstration at our shop. They come with the connecting lead to the BBC and a mains plug.
Ideal for word processing as its green or amber screen is very restful to read. Complete with easy-to-follow manual. No extra speech dictionary chips to buy! No specialised dealer upgrade' required! Auxiliary output socket provided for direct connection to an external amplifier. Order your [Versatile Speech Unit now!
The system consists of a mother board which fits inside the BBC and further daughter cards can be connected externally. The Internal card has the following features: In fact the fully populated board uses only mA. There is no soldering required. The board Is rigidly held by two 40 pin sockets and five support posts. A ribbon cable can be brought outside the computer and up to 8 external cards added. This enables the user to plug-in up to paged ROMs.
The cards have following features: The system comes with controlling software in ROM. The utilities supplied are as follows: ROMs present and files stored. This also reports on the amount of free storage space. This will write a test pattern into the memory and read it back out again. If a fault is found. It Is reported to the user. This test continues until Escape is pressed. All commands have similar format to the DFS and transfer Is possible between the two systems.
Winchester disc drives, clocks, etc. By racking the cards you eliminate the tangled mass of cables that usually accumulates around the micro. Please write in for further details and prices. What do the independent press say? Good value for money — Beebug Aug. It consists of over 14K of efficiently written machine code. It is entirely self contained and so does not require a utilities disc to function.
Please write in for full technical specification. We do NOT retail through any dealers. This makes using your printer with Wordwise much more convenient. You can define page top. All supported printers will now respond to form-feed etc. Operates with either parallel or serial interfaces. Please specify printer type when ordering so that we can send the correct function key strip. It will put on paper anything you see on the screen, including all Mode 7 facilities etc. The ROM also provides window setting facilities and two new OSWORD calls that allow mode 7 graphics pixels to be read and plotted using the standard graphic co-ordinate system.
Two commands are used to operate the dump routines: There are various optional parameters but you need only specify the parameters you wish to change. Unlike other dump ROMs the scale does not change with mode. Designed for use with the following printers: Prestel gives you access to an incomparable database covering almost every subject under the sun. There is Micronet with lots of free programs that you can download and run.
Details of clubs and user groups, a diary of meetings and exhibitions, news and reviews, technical information etc. There is Homelink with online banking. And there Is armchair shopping, travel information, entertainment, world news, sports news, weather information, electronic mail and lots more. A local phone call facility means no long distance phone calls to Prestel approx, phone cost is only 40p per hour. The Watford Prestel package consists of the B.
This totally machine code software: Disc and tape configurations fully supported. It is extremely simple to use as there Is only one command to remember. It will accurately dump any screen mode using multiple tones as required. Mode 7 is fully supported giving teletext graphics, double height etc. An overlay is provided to give comprehensive guidance to key functions. This mode is essential just before and after data transfer when both hand sets are replaced to reduce noise. Machine code or Data. Full facilities are provided for selecting between fonts etc. The disc includes examples of use and instructions.
Available on 40 or 80 track disc please state which required. These include underlining, bold, shadow, superscript, and subscript printing. Additionally, you can use proportional spacing on the EXP The printer drivers also extend the facilities in View to allow the use of pad characters. Please specify printer type when ordering. It is extremely easy to use through Its comprehensive menu system.
The simplicity is such that we do not feel the need to provide explanation on use in the written guidance supplied with the program. The first-time database user will rapidly become familiar with this package designed throughout to be simple and obvious. Despite the ease of use this system provides all the facilities needed for complex data handling problems. The length of database that can be handled is only limited by the total space on the disc.
You can have up to 20 fields with page length records up to bytes in length. Adding and deleting records, amend titles, field names and records. Sort on any field and search for any record or group of records in any field. The database may be re-formatted after creation, the system will re-write all your files for you automatically. You may add extra fields and extend the length of existing fields freely. Output formatting is very powerful. You are allowed 40, 80 or column output modes going to printer or screen. Selected fields can be put in any order on the screen or printer, either across the paper or down.
Output can start or stop anywhere in the file. Decimal fields are automatically totalled and records output are counted. Version 2, now on sale has improved input and amendments procedures giving full record edit as well as the 3 extra features. Calculations on numeric fields, and the ability to create sub files from your main files. It is also largely menu driven but has its own command language for file searching.
The 16K ROM contains all the normally required routines, with lesser used options supplied on the utilities disc. All input and output formatting is controlled through screen forms. A full screen editing system is used to define a form which allows tremendous flexibility in the format in which your data is displayed. It is very easy to change from form to form so that you can type in your data with one form, and examine it with others.
You will typically design several forms before starting to access the database so that you can quickly and easily see the fields of each record that you want to appear in the layout you decide on. The form system is also used for output to your printer. File Plus has a unique file linking system that allows the entire on-line storage of your system to be used for one database. This can give around 1. Presented in the form of a powerful command language with looping facilities etc. Full arithmetic operations are provided to allow the system to be used for statistical analysis.
By using the sideways RAM area for extra memory the following features are implemented: Then this piece of software is for you. This package offers many useful facilities that make the light pen a useful device to own. This program has many uses In education and at home. It is supplied with a comprehensive Instruction manual. Works with Watford, RH. DIY and many other Light Pens. If you have difficulties transferring your cassette software to your disc system then this is the answer. It is very simple to operate with Instructions supplied.
It saves you time and money. Full assembling and debugging facilities provided. This is coupled with facilities to completely enable or disable various ROMs in the machine including ROM manager itself. The commands given in the ROM: ROM numbers can also be used if required. This ROM is very simple and obvious to use. All the facilities are explained in the clear and detailed manual. It has all the normal memory editing, moving and relocating facilities, plus all editing is with a full screen editor allowing scrolling up and down memory, entering in Hex.
ASCII or standard assembler mnemonics. In use as a debugging tool, you run code under a total emulation system. Everfelt a desperate urge to set a break point in ROM? No problem - you can even have breakpoint on reading or writing locations in memory and on register contents.
The system fully supports debugging of sideways ROMs e. Beebmon can even run itself. In so doing you can nest Beebmon up to a level limited only by the memory size. Beebmon uses bytes of workspace, located anywhere in memory, even on the 1MHz Bus. Beebmon effectively uses no zero page workspace, so your program e. BASIC can use any or all of the base page. How does it achieve this?
By providing a interpreter all programs running under it exist in a vertual BBC. Emulation also allows immediate return to Beebmon command level by ctrl-escape no matter what code is being excuted at the time. All this exceptional power and flexibility is complemented by a clear and detailed manual included in a value for money price of: There is also a full set of labelling facilities available up to 3, labels , with the major locations and routines already labelled. It has all the features of a professional word processor yet is easy to use.
It allows you to display text on the screen in any of the following styles: Characters are printed in the same way as normal. Selection between the various fonts Is very easily achieved with Ctrl-V - press this followed by a font number and the output will continue In the new font. Beebfont ROM is particularly useful in display work with the characters produced at twice the normal size.
You can create your own character fonts with the editor supplied. The full range of character styles can be used, controlled from within the text. The editor and spooler program are supplied with the package, on cassette or disc. A twenty page manual is supplied. This allows good graphics and long programs to be combined. RS, keyboard or speech synthesiser. This allows very long text files to be printed while you are using 27 K of program and 20K of graphics!
It helps you to create your own application programs by the simple use of the Graphpad. Ideal for Educational use. Supplied complete with Cables. Manual and a two program cassette. Nearby lightning strikes, thermostats switching and many other sources put high voltage transient spikes on to the mains. This can lead to data corruption in memory and on disc and can result in spuriously crashing machines. Suitable for computers, Hi-Fi, Fridge Freezers etc. Surge current 2KAmp; max. Essential for serious computer users.
The storage box included stores up to 12 ROMs in perfect safety. BBC micro plinths have slots for maximum ventilation. Single height version is suitable for BBC and monitor. Double height version allows the disc drives to be used in the centre section or stationary, etc. The computer slides easily in to place, allowing easy access to remove the lid. The printer plinth is equally sturdy but without the cooling slots. This allows the paper to be stacked under the plinth with the printer on top - a very convenient way to work as it does not require the usual very deep table.
Supplied wired up with mains plug ready for use. Can be screwed to floor or wall if required. Very useful for tidying up all the mains leads from your peripherals. Allows the whole system to be switched on from one plug. The case is made of tough plywood, providing a very solid and safe way to carry your BBC micro. There is room provided to fit all the leads necessary behind the computer and manuals in the front.
Locks supplied with two keys. The unit has its own power supply so does not put heavy loads on the BBC power supply as do some other units. Connects directly to the 1MHz bus following all Acorn recommendations on addressing and bus loadings. It is a fully purpose designed and integrated package to simplify ROM development. The system is menu driven with many prompts to avoid any accidents. All these facilities and more are explained In the comprehensive and clear 15 page manual. The TEX erasers operate following the manufacturers specifications to give the maximum possible working life by not erasing too fast.
We use these erasers for all our own erasing work. Has automatic safety cut-off to switch off the UV lamp when opened. This works by creating a machine code patch that stays in memory while another program is loaded In. Allows any game to be used with joysticks. Supplied on disc or tape. Twin joysticks go to a single moulded plug, long leads provided. There are only 5 solder connections to be made.
Full Instructions are supplied. This board has been ergonomically designed to enable the user, easy further expansion inside the Micro, e. Double Density Board, Torch Board, etc. At Watford, we think ahead. This gives the User the ability to write a utility or language and upon pressing break have the utility or language up and running new ROM software can be developed and tested in situ. The Board gives the User, plenty of freedom to explore the possibilities of the new paged ROMs due in the coming months and offers them the chance to develop their own. All lines are fully buffered and the Board meets or exceeds all timings for operation in the BBC Microcomputer.
When fully populated, the ROM Board consumes less than half the recommended maximum current limit. Supplied ready-built and tested complete with fitting instructions. Supplied complete with our sophisticated Pen-Pal software on cassette see elsewhere in this ad. Makes full use of all facilities to discover the precise format of your protected disc so that an exact copy can be produced. Supplied with detailed instructions.
Please specify 40 or 80 track disc when ordering. Don't take pills — Use a Watford Electronics anti-glare filter I Considerable research Into the possible health problems associated with monitor screens has shown that eye strain, blurred vision, watering, itching eyes and headaches can result after prolonged use. The problems are caused by extraneous reflections which force the eye to continuously re-focus to try to ignore them.
The answer is our contrast enhancement, anti-glare filter which is similar to those which have been previously available on business systems, but at the low cost that you would expect for your personal computer. You will soon find the reduction in eye strain well worth your investment. Unless stated otherwise, please add 75p to all cash orders. Watford 09 23 These are the ability to pro- duce graphics using simple and clear commands and the ability to allow sec- tions of programs to be called by a name assigned to them and also allow- ing numeric values and strings to be passed Into them.
In First Byte this month we'll examine these features, and lay down the foundations for the construction of a simple but effective computer aided design CAD package. Both Acorn micros have what are termed graphics screens -in fact they have a total of five graphics screens, which differ in that they use varying amounts of memory and that only a set number of colours are available in each one. Selecting a particular graphics screen Is performed using the command: MODEn where n is the number of the mode.
Table 1 details the colours and amount of memory used by each screen mode. We can see from it that the 16 colours implemented on the Electron and Beeb are available all at once only In mode 2. To allow lines to be drawn on the screen two commands are provided: A particular point on the graphics screen is specified by using a co- ordinate system. The screen is divided off horizontally and vertically into lines, like a page of graph paper. The vertical lines, termed the Y axis, are numbered from 0 to The horizontal lines are numbered 0 to from left to right, and termed the X axis.
Thus any pos- ition on the screen can be specified or defined by its X, Y co-ordintes. The point , , for example. Is found by moving points along the X axis and then points up the Y axis. Figure 1 Illustrates the co-ordinates for each corner of the screen. The bottom left-hand corner has the co- ordinates 0,0 and this is referred to as the origin, as every movement we make will be referenced from this point.
If we want to move the graphics pen to the co-ordinates , we use a line like this: A square or rectangle Is simply four lines, each at a right angle to the previous one. A simple rectangle draw- ing program would be: At the end of each DRAW command the pen will be correctly positioned. Figure 2 charts each DRAW movement. Note also how the last DRAW command in line 70 returns the graphics pen to its original position.
Often when writing a Basic program sections are repeated several times. If these are quite short, perhaps just a couple of lines, it is easy to type them In wherever they are needed. Suppose we wanted to draw this four times on the screen. The Rexel Home Computer Starter Kit is put together by experts to help you get the very best out of your micro, especially if you are starting on the exciting business of creating your own programs.
Compatible with every cassette driven micro, it is available now at W. Smith, John Menzies and other leading suppliers. Also look out for the range of Rexel Computer Care and Maintenance products. You couldn't have a better start than that. The name-defining sequence is performed using the two statements DEF PROCxxxx, where xxxx is the name it could be of any length we wish to give that procedure. This Is standard practice as procedures are normally placed towards the end of a program listing. Add the following lines: Run the program to see the rectangle drawn on the screen.
The parameters refer- ences for the MOVE and DRAW com- mands within the procedure are fixed and cannot be changed, so the rec- tangle will be drawn in the same pos- ition each time. To avoid this we specify the parameters of each command as variables. Thus lines to become: Line therefore becomes: This approach Is still a bit untidy and can be cleaned up. To produce a rectangle all we really need to pass into the procedure is the MOVE co- ordinates and then the length of two adjacent sides. We can then let the procedure do the donkey work. So the final program to draw the four rect- angles looks like this: Just save each PROC to tape as you design it and then load it in as and when required.
Memory No of colours Mode required available 0 20k 2 1 20k 4 2 20k 16 4 10k 2 5 10k 4 Table 1. Colour and memory details Listing 1 provides a variety of pro- cedures that will perform the following: These procedures will be explained in full next month, but for the time being see If you can use them to draw your own designs. CALL me a car! As an educationalist take an opportunity to get right up to date with everything that's new in high technology and computers in education.
The new techniques aren't only for the science labs or computer classes, they cover all aspects of the schools curriculum, from geography to physical training. This exhibition, the first of its kind, is a definitive showcase for both manufacturers and users alike. You can see the best the world has to offer, compare specifications and collect literature away from the bustle of day to day activities. Entrance is free to anyone working in education and over 18 years of age.
Just clip the coupon below. For details of these and a booking form, tick the box on the coupon below. With a video monitor there is no tuner, sound and vision detection, or sound amplification circuitry. If I understand correctly, using a TV with a micro means that the micro output is first modulated, and then demodulated. Is this why the image begins to lack stability? Is this combination achieved by switching off the unwanted circuitry, and if so could the same thing be achieved simply at home, or is there something more complex involved?
But - and It is a big but - it is not a simple task, and the gains In picture quality are not great, for several reasons. First the picture tube in a TV is not the same as that in a monitor which gener- ally has a better resolution screen and with an anti-glare coating, so even if a television is modified the picture qual- ity is still not as good. Second, new colour TVs within the last two to four years have Isolating transformers fitted, as do monitors.
Older televisions have a chassis, which could become live under certain fault conditions. Should this occur while the computer was plugged into an unpro- tected monitor socket the computer could be badly damaged. Thirdly, earlier colour TVs 10 or Martin Phillips advises on TV modification, polishing programs, joystick commands, 3D printing, cassette care - and draws a house more years old have picture tubes which emit undesirably high levels of radiation. These are not to be recom- mended for close viewing with a com- puter.
Lastly, the Internal circuitry of tele- visions and monitors has Improved considerably In the last few years, and this too has contributed to a better pic- ture. Older TVs often need realigning to restore their original picture quality, and this in Itself is not a job for the un- skilled. There are some high voltages in a colour TV which can be dangerous. It Is a false economy as colour monitors that should give years of trouble-free use are coming down in price all the time and their cost compares well with a new colour TV.
As far as I can see they have no practical use sorry Robin! Most will only work on the BBC in mode 7. His program is given in listing 1. VDU commands from Robin Sasson. Try the effects stage from the working program. I know many users wish they could perfect a program, and when you first start this takes a long time, but it is sur- prising how you speed up with practice. Eventually you realise a perfect pro- gram Is unattainable as there Is always something more to be added or im- proved.
Line has been shortened as the latter part of the line did not accomplish much, since the program would still wait for an input at line Then three procedures were introduced: This made the pro- gram easier to read, and the responses for a correct or incorrect answer could be Improved with ease within each pro- cedure. Next I changed the position of the time test to after the right or wrong res- ponse.
This way the child would know whether the answer was right or wrong even if he or she was out of time. Here I made a mental note to include an out- of-time result with the score. Also the Instruction lines were altered to cater for the changes in the Input routine.
GOTO were redundant. They also avoided the need for long multi-statement lines, which would quickly have become cumbersome If extra effects were to be included. Listing 3 shows the next round of alterations. Then the results phase of the program was put into a procedure. Now It was possible to take account of the excess time taken and print It out if necessary. One second extra was allowed for each answer before printing an out-of-time message to avoid having silly re- sponses such as '.
Next the RND routines that filter out the number 1 were simplified, and I changed the maximum multiplier from 12 to The need to learn up to the 12 times table disappeared in the early seventies when decimal money was introduced and schools started teach- ing measurement only in centimetres and metres instead of feet and inches. When writing an educational program it Is necessary to look carefully at such aspects of the work being covered. However, It is surprising the number of teachers who still insist on teaching up to the twelve times table.
Listing 4 shows the final stage. The line of the program that displayed the question was printed in double-height, as was the answer. At this stage the program might seem perfect, but alas the changes introduced have made yet more problems. It is possible, for instance, to have '. Perhaps the easiest way is to Ignore a time excess of less than two seconds on the total. I pur- chased a Wordwise wordprocessor ROM, and on taking off the cover and keyboard I found I had only two spare sockets.
Not knowing what this extra chip was I tried to take it out, but I could not as it was soldered in place! The chip is totally blank. Can you suggest what I should do? So what is the chip and why should it need to be soldered into the socket? Even if it becomes damaged. It is better to fit a new socket. This was a good Idea, but all too easy to unplug, so they were probably sol- dered In place.
The only snag here Is that as an EPROM can be erased in ultraviolet light, the chip could be wiped clean and the computer would work perfectly well without It. In other words, leave it on a windowsill in strong sunlight for a few hours and all security is lost. This was covered in this column last February but for the benefit of Robin and the many new Electron users who have just bought the Plus-1 Interface and wish to use joysticks, and any new BBC owners, here is a tester for joysticks to check if they are wired correctly.
The BBC and Elec- tron with Plus-1 use the same com- mands and, as far as joysticks are con- cerned, the analogue port wiring is the same. The Acorn joysticks do not operate quite as expected. Moving the joystick to the left in the horizontal axis in- creases the voltage to the analogue socket, rather than reducing it as one would expect.
Figure 2 shows the joysticks correct connections for Acorn joy- sticks. Listing 5 gives a short program to display the ADVAL readings for either joystick, and can help to distinguish left and right joysticks why are they often not labelled? It can also be used to check for non-standard joysticks, or simply to see that the joystick works correctly. Do not worry If yours will not reach the maximum or minimum values and 0 ; they seldom do!
Any value within of these is usually sat- isfactory. Gives the effect of three-dimensional printing on Beeb or Electron give on the Electron, the maximum on the BBC being This means that it reads in steps of 16, whereas the Electron reads in steps of If you have non-standard joysticks they can be altered, provided the cases can be opened. It Is usually the hori- zontal movement potentiometer that is wired incorrectly. Check which potentiometer moves when the joystick Is pulled horizontally or vertically if that one is wrong.
There are three solder tags on the potentiometer with wires on each. Leave the wire on the middle of the three tags and unsolder the wires on each end solder tag, swap them round and resolder. The potenti- ometers are not particularly heat-sen- sitive and this task is not very difficult. Unplug the joysticks from the computer before opening the case to avoid damaging the analogue-to-digital con- verter chip. In this case the print is placed on the screen twice, the second just overlap- ping the first. The 3D effect is achieved by printing in different colours.
The pro- cedure parameters define the screen position, the string to be printed and the first and second colour numbers. The only reliable way I know of switch- ing the cursor on again after issuing the above command is to change mode. One had a blown internal mains fuse, the other had no internal fuse and the damage was more severe. Many people are careful to switch off the computer and the TV or monitor when they have finished, but do not realise that there is no mains switch In most cassette recorders.
If they are con- nected to the mains then they are on and live. If left on for long periods 48 hours is usually enough they will over- heat and the internal fuse will blow, or worse damage will be sustained by the electronics inside the cassette. Be warned, remember to unplug your cassette after use. Quicker on the draw ONE of the things that often puts me off typing in listings is long lines of pro- gramming or, even worse, long lines of DATA statements. I never manage to type them in correctly, and it Is difficult to find where the mistakes occur.
DATA statements are very useful and can save the programmer much time. If they are included In the listing with a little thought, they are easy to read and follow what is going on. There are two ways to stop the rou- tine trying to fetch another set of numbers when the picture is complete. One is to tell the computer how many sets of data it will have to read in the first place.
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This will be stored as a number at the start of the program, eg: By using REM statements, leaving a line between sections, and by not put- ting a long series of data on each line, the program is easy to follow, and hence is easy to correct or adapt. For Instance, try adding windows, or a chimney to see how extra data can easily be Included. It is designed to reduce the risk of their picking up exter- nal sounds, which cause errors.
He recommends putting window draught sealing tape around the telephone receiver where It snaps into the coupler. It is not easy with Wordwise to space out a document correctly, but by redefining the space to a small dot in the middle of the line to avoid confu- sion with a full stop , it is easier to insert the correct number of spaces required. This tip will only work when Figure 3. The house that READ. DATA built the document is viewed in mode 0, and does not affect the mode 7 display or the final printed version.
The space is redefined by typing the following line: We have somehow made room for hardware stocks. Home computers, disc drives, printers, monitors, and now a very special offer R. All major credit cards accepted. Offer subject to availability Soft Shop Ltd. Major articles, plus Regular program features including games and useful utilities. BEEBUG now has some 20, members and has achieved a high reputation both in this country and abroad. Define individual graphics characters with this useful utility for use in your own programs.
Computer Concepts by mail order or by telephoning with your credit card number, or from most good BBC micro dealers. Access, Educational Orders, and Official Company orders. The number of rows is automatically set from 5 to over depending on the columns declared Both numeric and alphanumeric data can be stored in any cell and can be of any length up to characters.
There are a multitude of uses for this program from accounts to diaries, club or personnel records etc. It allows for standard pay. We are pleased to offer you a wide range of products prinnarily for the BBC microcomputer software, firmware and hardware for your computer system. An ace always counts as 'V. Queen or King counts as 10' when its value is added to others but ranks in normal sequence when scoring runs. Selective printing any number of labels, repeat, stationery or fan fold. Many BBC programs are compatible.
This full colour 32K ROM and RAM computer with text and graphics includes a cassette input, and a multi-way connector for the addition of expansion units containing interfaces to additional hardware. The Electron comes with free introductory cassette containing 19 programs including a number of exciting games. The NEW advanced home computer designed with first time users in mind. Full size professional keyboard, four cursor keys, powerful 16K RAM, easy to use and program. Computers 7 Windsor Street Uxbndge Tel: Bridgend Mid Glamorgan Tel: It Is superior to many popular commercial units.
On another point, the inside of the BBC case can be sprayed with zinc to radically cut down the interference radiated from the computer it- self, the other side of the coin being that RF Interference from transmitters is less likely to upset the computer. Packet Radio is the most exciting thing on the horizon for computer-directed radio amateur communications. Radio amateurs throughout the world are still discussing suitable standards, although it looks as if the AX25 standard could well receive worldwide support. I hope these remarks will be of use to readers.
You also gave the suppliers of the good- ies a gift of an advertisement. To the unknowledgeable reader it all looks fine, but to a licenced amateur call sign; G4PLW I know your list of equipment Is not necessarily the best available and cer- tainly not the cheapest. I have both items: Peter Walker Middx Hitting out at high prices Sir, I would like to voice criti- cism over the cost of purchas- ing peripheral equipment for the BBC micro.
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Without a doubt the model B is one of the best eight-bit home micros, and with its excellent operat- ing system and Basic it is a real pleasure to use. For the manufacturers this marketing policy holds three dangers. Against these BBC equipment appears grossly over-priced.
Second, the advent of blt home micros looms. Micro enthusiasts are just one sector of the magpie-like consumer group that rushes out to buy the latest, brightest, fastest new product. If it costs too much to upgrade your existing micro, people will simply dump it and buy a new all-sing- ing all-dancing bit machine. The basic coinage of micros Is RAM. With more RAM, the greater the options, more can be done. Against these even the model B looks puny. Next year second processors? I Hayes Surrey expensive Sir, I would be interested to know why the second pro- cessor Is so expensive.
Interfaces and other chips. However the second pro- cessor just seems to be a pro- cessor with memory and the Tube Interface, so why the high price? The first concerns Mr Howard, who wrote in the September issue asking about the addresses of the floating point routines in Basic; the July Issue of Persona! Computer World carried the information. Second, people who play Level 9 adventures on the second processor will have discovered by now that this produces at best garbage.
There Is a simple reason for this and I have worked out a short Basic patch which should be loaded in and run after the body of the adventure has been loaded into the second processor of course. Then save the amended ver- sion onto disc before using. The patch is program 1 below.
Note that the code relies unwisely on the carry flag being clear at the start of the addition causing ADCffI to add two rather than one when the carry flag is set. Roger Hill Guernsey Level 9 has asked us to point out that this patch will only work on early versions of the adventures. The latest adventure, Return to Eden, will run on the 2P. It deserves a further airing for the benefit of readers who may have missed it. Indeed, It was only while browsing through some old copies that I realised its potential.
Type listing 2 in as shown for use with disk and run it save it if you wish. Conditions are then such that you can load other programs, operate Escape and Break, while still retaining definitions of up to 40 user-defined keys. Operation of fO cycles through four sets and displays the cur- rent set on screen. If you wish to retain this new definition, f8 in set 4 should be used. Lines and are useful variations to re-arrange the Break key so that time is saved when program writing. A better way to make use of the definable function keys: I know this means the com- puter has run out of memory, but the program must have worked before It was put in the magazine.
There are several screen modes on the Beeb and Elk and these all require specific amounts of user memory to operate In. For example, mode 2 requires 20k -more than two-thirds of the user memory. If mode 2 Is selected only a small amount of memory is left for you, the programmer, to use.
If there is not then the Bad Mode error Is printed. How do you get around this? If you have a disc inter- face fitted this will gobble up precious user memory. The sequence is therefore: Now enter your program, save It to tape in case of possible cor- ruption, and try running it. Nine times out of ten this will solve the Bad Mode problem. A further problem now exists.
You cannot readily use discs because as soon as you try to save the program to disc the disc filing system will re- claim Its memory and corrupt your program. The only way to counteract this Is to enter the program at the normal PAGE value, save it to disc and then write a downloading program that will move the program down-memory automatically - Martin Phillips described the technique in the June issue page For example, modes 4 and 5 need only half the memory required by mode 2.
So try experiment- ing with different modes. Adrian Frost Fife 0 ln the beginning The Proton, as originally envisaged, would have been without many of the features we ail now know and love on the Beeb. The contract between the BBC and Acorn meant that the machine had, for instance, to be able to pro- vide teletext type - thus, Acorn had to go away with its Proton and design mode 7 onto a chip. By post- complete the coupon with your requirements and return to: A quality product, it is extensively industry-proven in major systems applications all overthe world.
Now available for the home, educational or office user by mail order from Computamate, the TEAC 5V4" Disk Drive guarantees trouble-free high speed data access every time; and what more could a micro ask? Enquiries from Dealers and Educational Authorities welcome. However, when I want to read the file, I get an error message.
Could you please solve my problem? Thank you for your letter, but unfortunately you do not explain why you are writing these programs, which would have helped me work out the best answers. Your program 3 Is logically correct, but I wonder if It does what you want, because all it does Is place a single byte in the file. For example, if you entered: You can see that line 40 only sends the bytes for the variable I.
I would prefer program 3b which Is almost the same as yours, with a couple of addi- tions. Finally, line saves each set of Infor- mation each record to the file. Now for your second listing program 4. Unfortunately, it does not operate correctly. Looking at line 50 and 60 shows that you seem to be expecting ail the information saved In program 3 to be brought back into the com- puter for use with lines 50 and Also, the infor- mation that it does save, the Item number as a byte, is not being used in program 4.
Line 20 can be removed altogether and line 40 can be altered to say just: Program 4b is one solution. This does the calculations with the data filed in program 3b. When I used the two programs to make a short file, the final result looked like figure 1, although It could be put Into columns using the TAB com- mand several times in line There is, however, one thing that really puzzles me. For a machine almost perfectly suited to educational use, why is there such a shortage of good educational software? I have seen quite a few pro- grams In magazines which purport to be educational, but on further investigation most are poor indeed.
I have two sons aged eight and 10 and we have gathered a collection of programs that are based directly on work they are doing at school. I ask myself though, could it have something to do with profit margins? By that I mean programs that education auth- orities are being charged a lot of money for would simply not sell for such prices on the open market. I for one certainly hope so. R Hughes Essex Adventure query Sir, Much has been written on the subject of misleading cassette packaging and adver- tisements, as the game is often nothing like the fancy pictures and exciting description.
There does seem to be a perfectly logical answer: But what about text adventures? It would be quite a daunting task to try and represent them on a wall, let alone a tiny cassette Inlay.