Supertalker

Personal Computer News

Geof Wheelwight

Ian Scales

John Lettice

PC MICROPEDIA VOL 13 PART 2 PERIPHERALS Your guide to microcomputing add-ons. PERIPHERALS BUYERS GUIDE Once you've bought your micro, you'll soon discover the purchase of that central piece of hardware wasn't even the half of it. You'll start learning about the capabilities of your chosen machine, and as you go you'll find you want to do a number of things that require add-ons. You may want to handle large quantities of data, for example, or you may just want to handle it faster, in which case you'll need a disk drive. And you'll want some hard copy output, so you'll need a printer. Not just any old printer either, because you may want to have a specific kind of printout. You're also likely to be having trouble negotiating the use of the domestic TV - so can you afford a monitor, and if so, how do you choose one? Once you've got it all, your micro may want to phone up its mates and tell them all about it, so what about a modem? What's available for your micro, and how do you choose the best? All this and more will be revealed in our peripherals buyers guide. ADD-ONS ADDED UP Microcomputers are not very useful without other pieces of equipment for them to control or be controlled by. In the world of computers these pieces of equipment are known as peripherals; a clumsy and unfortunate term but one which we're stuck with. Peripherals aren't just things which you add on as a luxury or afterthought as the term may imply. In a technical sense just about everything apart from the processor chip itself is a peripheral - the RAM memory is a peripheral, as is the keyboard, the various interfaces and the video circuitry. These features instruct or are instructed by the logic produced by the processor and the software. This section deals with what we will call add-ons. Add-ons are always peripherals, but they are peripherals of a special kind in that they are designed to be optional extras, hardware enhancements. They are the bits of equipment you are likely to want to buy once you have come to grips with Basic programming and are looking for new and interesting ways to use your machine. Add-ons are products such as printers, cassette tape systems, disk drives, monitors, speech synthesisers, graphic input devices and devices which enable communication over the telephone to another computer or receive information over the airways from a broadcasting database like Oracle or Ceefax. This Micropaedia will look at a range of off-the-shelf peripherals for a variety of machines and give you an idea of the sort of things you can buy, what you can use them to do and what you should look out for when you're deciding which item to purchase. In many cases an add-on will require an interface to enable it to communicate with the host computer. The two most common standard interfaces are the parallel Centronics interface and the serial RS232. Parallel interfaces send information a byte at a time down a ribbon cable (the bits which make bytes travel in rows like a line of cars driving side by side down a multi-lane roadway during rush-hour). The serial interface is rather like a one lane off-ramp going from our imaginary multi-lane road, it straightens our rows of bytes into a single line of bits and sends them off one at a time. The serial interface is a necessary prerequisite to communicating over a telephone line, though it is often used to send information to printers and other peripherals as well. A computer like the BBC Micro is well endowed with a host of interfaces to enable it to talk to disk drives, printers and different sorts of display units. However, in comparison with many of its competitors the BBC is an expensive micro. When you buy a less expensive micro like the ZX Spectrum, for instance, you'll find that it's cheap because most of these I/O (input/output) features have been left out of the design. To compensate, the cheaper machines often have an edge connector. This is really just an extension to the micro's bus (the parallel pathway taken by the data around the circuit board). With the provision of the edge connector, Sinclair Research was able to offer add-ons like the ZX printer, Interface 1 and Interface 2. But the problem with this approach is that the user is limited to add-ons which are specifically designed to be used with a particular computer. You can't (without expensive adaptions) use the ZX Printer with other computers, and you can't use just any old printer with the Spectrum. It wasn't long, therefore, before independent manufacturers were producing what are known as standard interfaces as add-ons for the Spectrum so that users could configure and use a wide range of standard add-ons, especially printers. But even hobbyist computers with interfaces can suffer from compatibility problems. Commodore owners, for instance, will be well aware that the interfaces on their machines are not industry standard ones, and they are therefore limited to buying printers and disk drives from Commodore. So it's not surprising that there are several interface adaption units now on the market that enable the Commodore interfaces to communicate with standard printers. Joysticks are becoming especially popular add-ons for most machines. Many computer manufacturers seem to have been caught napping, under-estimating the interest in action games. Providing the necessaries has often fallen on third-party manufacturers. The Spectrum, especially, has been deluged with various joysticks and interfaces to control them. Again, especially with the Spectrum, the problems concerning standards comes to the fore. Fortunately, Sinclair has now released its Interface 2 for the Spectrum. This unit, which plugs onto the edge connector, allows you to plug in standard joysticks, it also has a games cartridge slot for Sinclair's own range of games. The importance of Interface 2, is it will enforce a standard on software writers. Before Sinclair's release the different controllers available had different ways of controlling the screen action, so a game written with one set of joystick routines wouldn't necessarily run with another. Most of the games produced for machines without joysticks as standard were configured to use a combination of key depressions to control the action on-screen. So some of the joystick controllers on offer get you to configure them so they know which key is supposed to be depressed and send the program the character string it's looking for. On other machines the joystick controller is no problem. On the BBC, Atari, Commodore and so on there are joystick ports as standard. But users are not limited to simply using the joysticks on offer from the manufacturer as there are a bewildering variety of custom sticks available from the third-party people. Some joysticks use potentiometers instead of plain old contacts. This tends to give you a greater degree of precision. Some sticks have been designed to be hand-held, with the stick on top of a pistol grip handle and a trigger as the fire button. Others are table-top types, also with a pistol-grip but with a button on the top for the thumb to fire. Some games controllers aren't joysticks at all. The Apple, for instance, can be fitted with a track-ball device instead of a joystick. Communications is another popular area to expand your machine into. The costs of the devices necessary to hook yourself into the telephone network are coming down in price rapidly as chip manufacturers produce the wherewithal to do it on smaller and smaller slivers of silicon. What you normally need is an RS232 and a modem. The modem can be either directly or acoustically coupled. The attractions of the modern have increased recently with the establishment of Micronet, a specialist information provider on Prestel which gives the latest micro news and provides a large array of free software which can be downloaded by its subscribers. Whatever the sorts of add-ons you wish to acquire, the most important consideration is that of compatibility. As you can see from the run-down above, compatibility (or lack of it) is the thing which probably promotes the most nail-biting among users. This consideration applies most of all to storage. There have been some wonderful and innovative storage devices touted recently. Unfortunately, these are of much less use to the average punter if they are not widely supported by the people who produce the software. In many cases it will be impossible to move your existent games and commercial programs across to your new media as the programs will be protected. With add-ons, get assurances that they are going to do the job for which you require them before money changes hands. -- Interfacing is a crucial question for the micro owner. A cheap micro like the Spectrum is cheap partly because it doesn't have a range of interfaces built in. You can buy interfaces for it, both Centronics and RS232, but if you just have the basic machine the only printer you can connect it to is the ZX Printer, which is cheap, cheerful, and a shade illegible. With a BBC, on the other hand, you get RS232 and Centronics interfaces built in, so you can hook it up to an Epson, say, or the Shinwa CP80 quite easily. The same principle applies to other add-ons, such as joysticks, disk drives and monitors, so if you want to hook your micro up to a lot of things, and you have one of the machines that is short on interfacing, your first step is to get some. -- Printers probably offer the most diverse range of choices to people who want to do a spot of adding on. They can be divided roughly into three broad categories. The most popular type of printer is probably the dot matrix. This uses a column of tiny wires which punch through ribbon creating each character as a matrix of dots. This technology produces the best possible of all printer worlds, with fairly high-quality results when printing text, the possibility (with the right software) of doing graphical output and a reasonable speed and price to cap the package off. Dot matrix printers usually achieve at least 40 cps (characters per second), and more outlay will get one which can do up to 160 or more cps. Most hobbyists would probably find 40 to 80 cps quite adequate. Printers with this sort of speed and reasonable flexibility can now be bought for between £200 and £300. Although dot matrix text is eminently readable, it's not thought to be quite up to the standard of the traditional typewriter-type of output, which of course uses solid moulded characters stamped through a ribbon to create a precise character image. To cater for people who plan to use their printers mostly for turning out letters there is a category of printers called daisywheels. These are basically typewriters designed to be used by computers. Enough print arms to support the alphabet and various special symbols radiate from a central hub. The wheel is rotated back and forth so that the desired character appears under a hammer which then strikes the moulded character through a ribbon and imprints it on the paper. The assembly containing the wheel and hammer is drawn back and forth across the page as the paper is fed through the mechanism. Unlike dot matrix printers, which use a tractor mechanism to feed through continuous paper, the daisywheel is usually set up to accept single sheets. Because it's a very mechanical device it's also slower than a dot matrix when it's priced in a similar bracket. Money will buy you a fast daisy, but it is usually a lot of money. There are now a few daisies under £500, and these tend to plod along at about 12 to 15 cps - usually enough time to walk around the block while a reasonably sized piece of text is being printed out. Considering the noise a lot of them make, this might not be a bad idea. There is a third category of printers which we can call 'alternative technologies'. These are usually either electrostatic or thermal. As a rule, if you get rid of as many precision moving parts as possible you keep the price down. These printers often cost around £100 or less like Sinclair's ZX Printer, an electrostatic printer which selectively burns a special coated paper as it passes through. Tandy has just released the TP 10, a thermal printer, which achieves much the same result by applying heated elements to special paper. These printers usually work on narrow rolls of paper, and are targeted at users who only want to have a hard-copy of listings and dabble with a few graphics. There is no 'best of all worlds' in buying a printer. Without spending a gigantic amount of money you are going to lose out on either print quality, graphics ability or speed - it's very difficult to get all three together. The following examples are typical of what's available on the market. The different capabilities will give you an idea of what you should look for in the printer you require. -- The CP 80 should serve as a similar pointer to the dot matrix market. We think it's a particularly nice little printer and it is competitively priced. The first thing you notice about the CP 80 is that it is light and fairly small. The second thing you notice is that the paper is fed in by the tractors from the rear of the printer rather than dragged out once it's been printed. This seems to work without a hitch, and enables you to start a new lot of continuous paper without wasting a piece by feeding it into the tractor mechanism. This printer has both a tractor and normal typewriter-type rollers, so you can use single sheets of paper as well. There is the normal clutch of buttons and warning lights. The printer is capable of about 80 cps. Another interesting feature is its carbon film ribbon which is slightly more expensive than your normal dot matrix ribbons, but this drawback has been allowed for by the manufacturers. The penny pinchers among us are able to change the ribbon in the cartridge up to 4 times instead of throwing the cartridge away. This ribbon gives very sharp and dense text. The dip switches are inside the machine. Using these and the control codes you are able to do such things as choose between normal, enlarged, condensed, emphasised, double strike, subscript, superscript and underline type-styles. You can switch the character set to italics, and do bit image graphics superscripts, subscripts, alter line spacing in 216ths of an inch, change the form length and the line length and line spacing. -- When the Juki 6100 Daisywheel printer was released in May 1983, it caused as much of a stir in the industry as any printer is likely to cause. Here was a daisywheel with lots of nice features, high-quality print, and all for a price of just £399. Previously you would have been shelling out at least twice as much for a printer of similar quality. The Juki can provide you with a benchmark. You are unlikely to find anything much cheaper with the same features. If you look at more expensive daisies you can work out for yourself whether their features are worth the extra cost to you. The Juki uses standard Triumph Adler daisywheels and IBM ribbons, it's a plodder, not a racer, and churns along at about 17 cps, in doing this, however, it tends to make a high pitched whining noise which is minimised to some extent by lots of insulation on the interior casing - still, you can't have everything. The maximum paper width is 13 inches and this can be fed in sheet form or you can use continuous stationery if you're that way inclined. The pitch (that's the number of characters per inch) can be varied between 10, 12 and 15. You can buy a wide selection of wheels featuring different typefaces and different pitch sizes. The all-important dip switches (there are 10) control the automatic line feed, form length (it can be 11 or 12 inches) and the number of lines per inch (6 or 8). You can specify continuous or cut paper. In addition to the dip switches, of course, there is a big selection of control codes. They enable you, among other things, to backspace by one column, do an upward or downward paper feed and to insert sub or superscripts. You can do bold or shadow printing, set the left and right margins as well as the top and bottom and you can get the printer to print its extra symbols on the daisywheel. -- Storage is a vexing problem for the low-cost micros. By their very precise mechanical nature, magnetic storage devices must be priced at a level which usually puts them completely out of the scale with the micros at the bottom end of the market, it's difficult to justify linking up a full-scale disk system costing several hundred pounds to a £99 Spectrum, for instance. Yet cassette tape storage is so slow and inefficient, that there have been many attempts to find a middle course between the cost of a floppy disk system with all its random access and variable length file-handling capabilities and the out-of-depth domestic cassette tape recorder, which, after all, was designed to play analogue music tapes. Despite the problems, however, prices in the disk drive area are falling, due mostly to increased volume and more streamlined distribution methods. There are, after all, a lot of Dragons and BBCs out in the field and last year's computer buyers are often this year's disk drive purchasers. It is possible to buy single 40 track drives below £200 now, but the chances are that this particular technology is not going to get much cheaper in the near future. Disk drive buyers must pay careful attention to the details concerning compatibility with existing disk operating systems and disk interfaces. The point is that a disk drive is only really useful if it gives you access to a wealth of off-the-shelf disk-based software. Always seek assurance that the program you want to run will be formatted for the drives you are buying. And don't be too certain that you can save your existing tape-based games and programs to the disk. Many of these are protected by the program to make them unlistable so they can't be copied. What makes the floppy disk drives so expensive is the precision components necessary to rotate the disk at the correct speed and align it in the spindle at the correct angle. Then there is a stepper motor which must position the read/write head at exactly the right position over the disk as it spins. -- When it comes to alternatives, the most successful so far must be Sinclair's Microdrives. The Microdrives can be used by the Spectrum with the addition of the Sinclair Interface 1. Instead of a disk, the drives house an endless tape cartridge, so there's no stepper motor and no finicky alignment problems. The tape is wound right through in about 10 seconds and because it's wound off the middle of its spindle and simultaneously wound back on the outside it's ready to go through again immediately. Because of the speed of the data transfer (about 16 Kilobits per second) it can do a good job of simulating genuine random access. ie you can specify a file and the system will go through the tape reading all the information and keeping the relevant sectors in its memory. Unlike a cassette tape system it has an operating system which allows it to maintain variable length files. If you save a file and then save another one or two after it, you have no way of increasing the length of the first or second file without saving a new version on another tape. As with a disk, the Microdrive splits its media up into segments of 255 bytes and then splits up the file and writes them to as many of these segments as the length of the file requires. Then if you load the file and perhaps add more information to it, the operating system will simply save it to its former segments and any other free segments it can find on the tape. After you've been using the tape for some time loading, changing, resaving and deleting files, all the sectors of all the files will be scattered right over the length of the tape. It's to be hoped that the Microdrive will be the forerunner to other such devices for other computers. At the moment it is only being sold by Sinclair on a strict rotation basis to mail-order purchasers of the Spectrum, but it shouldn't be long before it's readily available to one and all. Once this happens it's almost inevitable that enterprising concerns will engineer interfaces so that other machines can also take advantage of its cheap price. -- The Hobbit was released earlier this year as a halfway house between disk and cassette for BBC users. It gains access to the BBC micro through the user port and uses Philips digital microcassettes to store data. Its operating system is housed on a ROM which goes into one of the free 'sideways' ROM sockets in the BBC. Once installed, the operation of the drive is completely under software control. Data is loaded at about 750 bytes per second - much faster than a domestic tape recorder, it has a full set of file handling commands and operates in much the same way as a very slow disk drive. -- Choosing a modem at the right price is becoming an easier proposition these days as the prices of the components which go into the things plummets for the manufacturers who put them together. Modem stands for MODulator/DEModulator, and its task is to act as the go-between for the digital computer and the analogue telephone system. A modem takes the digital pulses that race around a computer and converts them into modulated tones that can be sent down a telephone line. The digital pulses first have to be straightened out by an RS232 interface into a serial form (one bit at a time). If your computer has an RS232 interface it is a fairly straightforward task to put a communications system together. Most standard modems will plug straight in. If you haven't got any interfaces on your machine then the procedure is a little more problematic. The Spectrum, for instance, now offers two fairly reliable routes to the wonderful world of telephone communication. The addition of Sinclair's Interface 1 (when it becomes generally available) will enable you to directly connect the necessaries as Interface 1 has its own RS232 interface. Alternatively, Spectrum users can opt for the new VTX 5000 from Prism, which has built-in RS232 and software and plugs directly into the Spectrum's edge connector. For other machines there is rather more diversity. There are dozens of standard modems on the market to choose from. Modems sort themselves out into two broad categories. These are acoustically coupled modems and hardwired or directly coupled modems. As the name suggests the hardwired modem is plugged directly into the telephone network via a standard Telecom wall socket. The acoustically coupled modem attaches itself to the telephone's handset where a speaker in the coupler opposes the handset's mouthpiece and a microphone opposes the earpiece. The acoustic coupler has the advantage of being more portable than the hardwired modem and, up until recently, seemed to be slightly more popular because the prices of the directly-wired variety were higher. This was presumably because of the stiff regulations placed in the way of directly connected modems. (Telephone companies are always wary of allowing items running off the mains to be attached to their expensive networks. Think of the damage a short-circuit could do by sending 240 volts into the telephone system). Acoustic couplers can also suffer from background noise corrupting the data. Direct modems are often capable of dialing their own numbers and automatically receiving a call and accepting data. Terms you will encounter when buying a modem are likely to include half and full duplex. Full duplex describes modems which are capable of simultaneously sending and receiving data. Why, you may ask, should a modem want to do this, it acts as a check on the integrity of the data being received at the other end. The full duplex computer receiving the data is immediately sending it back again to check its validity. The sending and receiving is done at different frequencies so that the data doesn't get tangled up. Half duplex mode only sends data one way at a time. Because it is only using a single area on the bandwidth it is less likely to be the victim of interference. Most modems are now capable of both half and full duplex. Baud rate is another bit of obscure jargon guaranteed to confuse and frustrate the budding communicator; Baud is a measure, of the number of modulations per second (the modulations represent the binary code). It's important to know what the baud rates of your likely digital correspondents will be before you purchase your modem, as you can't always select a full range of transmission or receive speeds, especially with the cheaper products. Micronet for instance, a micro enthusiast's database on Prestel,operates at 1200 baud receive and 75 send (from the user's point of view). -- Prism Microproducts is at the forefront of the new generation of (mostly) hardwired modems. PCN recently reviewed its latest release, the VTX 5000, an all-in-one communications package for the edge connector of the Spectrum to enable it to hook up to Micronet. (Issue 30.) Prism's general purpose hardwired modem costs £89.95, and we'll look at this to give you an idea of some of the features you should expect to get for the price, now that Prism has set a new standard in value for money. Although it's been targeted at Prestel and Micronet, this is no ordinary Prestel modem, it does have the requisite 1200 receive/75 transmit baud rates for the service, but it also offers 1200 baud in half duplex, opening up the possibilities of micro-to-micro communication over the telephone system. We tested this one on a BBC using the standard Micronet terminal software and it performed faultlessly. Don't pay more than £89.95. -- Joysticks are a subject close to the hearts of many micro enthusiasts. It was (probably still is) widely predicted that action games would be a flash in the RAM phenomenon like the hoola hoop - a quick craze that will die out once users realise the joys of programming. Indeed this seems to have been the thinking behind the Sinclair computers. Both the ZX81 and Spectrum were released without any type of joystick facility. The idea was that the users would learn how to do Basic programming, and their widespread success seemed to bear this idea out. But it's probably true to say that the Spectrum and ZX81 sold despite their being stickless - because they were affordable while their games-playing competitors were out of reach. It wasn't long, in the Spectrum's case, before manufacturers produced joystick controllers. Sinclair Research didn't take too long to cotton on as well, and released the Interface 2 about three months ago - it's reported to be selling well. Most other micros have joystick facilities as standard. Those that don't, like the Spectrum, have at least one independent supplier of controllers. But the good news with joysticks is that once the controller has been sorted out, compatibility isn't too much of a problem. Add-on joysticks for the portless computers seem to have settled on the 9-way D-Plug joystick socket arrangement. Computers like the BBC and Dragon have their own separate plugs and sockets, but the computer manufacturers, for once, seem to have left the field open to the third-party manufacturers. At best they only make a token effort in providing their own joysticks which, if available, are usually fairly cheap and nasty. Sinclair hasn't even attempted to provide joysticks, just the controller with a D-socket so you can choose your own. It's pretty easy to tell a good, rugged, well constructed joystick from a flimsy, liable-to-fall-to-pieces one. Ruggedisation (as the computer industry likes to call anything that prevent kit from disintegrating at the slightest excuse ) is of prime importance when you're picking a joystick, especially if you're the excitable type and actually think you are repelling invaders. Here are three joysticks which illustrate three basic approaches to the problems of controlling screen objects in a precise manner. All three are very solidly constructed and should stand a lot of abuse. -- The Flight Link Joystick takes yet another approach with its potentiometer joystick. Instead of a mechanical assembly closing one or two of four contacts to return the appropriate character strings to the processor, the Flight Link has two potentiometers on a universal joint mechanism which sit at right angles to each other. The potentiometers fix the desired direction of movement by plotting an x/y co-ordinate according to the rotation of the potentiometers. To you or me, this means that there is no spring loading. Instead, the stick moves freely on its axis and stays where you leave it. The stick itself is very small and you are required to be dainty rather than brutish to make the best use of the system. Thumb and forefinger rather than clenched fist is the way to handle this one. You can keep it on the table or hold it in your hand, and it's ruggedly constructed so you can probably drop it a few times as well. Available from Flite Link Control [redacted]. -- Kempston's Competition Pro is a good, solid family saloon type of joystick. Nothing flash or innovative here, just attention to detail and precise control. The stick's 'throw' (the distance you have to move it to get things moving on screen ) is very short, and this means that its base is capable of supporting the assembly without you having to tie up your remaining hand to prevent it toppling over as you dash to the other side of the screen to zap an alien. This also makes it extremely responsive. Kempston claims the shaft is nylon covered steel, which sounds impressive. There's also a comfortable knob on top so you don't develop a permanent extension to your life line - often an unfortunate side-effect after extended playing with some of its angular competitors. The firing buttons are 'hair trigger' and the merest hint of push will set off whatever is supposed to be set off. The Kempston features a standard D-plug. Available from Kempston [redacted]. -- The Spectravision Quickshot changes the joystick recipe with a helicopter-style grip and a choice of fire buttons. Many people prefer this sort of grip to the more conventional Kempston type because it's easier to keep the whole assembly in the one position when you are playing. Damage is done on screen by either the thumb or one of the fingers of your free hand. The Quickshot also proudly features what is described as a contour groove to give your free hand better purchase around the auxiliary fire button on the base. If all this doesn't keep the thing steady, you can resort to using the suction caps on the four corners. Accuracy, again, is very good and the triggers are very responsive. Again the standard plug to suit Atari, Commodore, NEC and Spectrum (Interface 2). Available from most Atari and Commodore dealers. -- Speech synthesisers are just starting to graduate from being experimental whizz-bang gadgets, with which you can amaze and delight your friends, to everyday features. Not run-of-the-mill you understand, but at least useful aids in their own right - especially to enhance the realism of games, both the action and adventure types. They also appear regularly in educational-type products such as spelling aids. Up until recently it was left up to the users to program speech into their own programming creations, usually the user (listener) is given a couple of levels of entry into the system. At a basic level there is generally a set of tailor-made words in ROM which the user can just POKE into a program. These may include the letters of the alphabet and the numbers and perhaps a few Basic keywords. Some synthesisers feature a second level. Here you can actually phonetically concoct your own words by typing allaphones. Allaphones are alphabetical symbols which stand for the 64 (yes only 64) distinct sounds we make when we talk. By combining allaphones with suitable pauses you can laboriously put your own words together. It gets better with practice and not surprisingly, even if you don't learn anything about computers doing it you do gain an understanding of speech. The slightest millisecond pause makes all the difference between a word making sense or sounding foreign. -- The Namel Supertalker is a good all-rounder. It can make use of phonemes, another form of coding the human voice's composite sounds, and it also has its own built in 550-word vocabulary. It's also very versatile because, unlike many of the other products, it works through an RS232 interface and so can work with any micro which possesses RS232 output. The Supertalker has its own processor and RAM, so you can download a custom vocabulary and call up the words you want when you want them. Its sound comes from a built-in speaker driven by a small amplifier. Not the cheapest but certainly one of the best. -- The BBC Microcomputer, with all its extra nooks and crannies, can play host to a couple of ROM chips supplied by Acorn; which impersonate veteran newscaster Kenneth Kendall. No untidy black boxes for Acorn, Kenneth is tucked right out of sight and his voice comes through the BBC's built-in speaker. You can access 165 words provided in the PHROM (Phrase Read Only Memory). To make up your own words you have access to what Acorn calls compound words, made up by combining two or more words from the 165 word vocabulary. Silent periods can also be generated. You can write in assembly language straight to the processor, though this is a very tedious process and can use up a disproportionate amount of the already limited user RAM on the BBC, so most users will probably stick to the words provided. The sound is recognisably Kenneth Kendall, though he does sound a little muffled. -- For the micro that has everything, you could do worse than buy it its own little robot. The Zeaker Turtle measures just 5in by 5in by 2in, and not only can it move around, it also has an artistic bent - in fact drawing on the floor is its forte. The Zeaker can work with the BBC, Spectrum or ZX81; the latter through special adaptions for the edge connector. You control it through a high-level language called Snail Logo. This gives you commands like Forward, Left, Right, Pen up, Pen down and soon on, and all this can be looped and repeated. It's very simple, but it is fun to use and the beauty of it is that it provides the budding programmer with very positive and immediate feedback. You are actually getting something concrete happening through you own programming efforts. The Zeaker can also turn out reasonable graphics - nothing like a plotter of course, but with care the results can be quite pleasing. Contact Colne Robotics [redacted]. -- The Beebplotter is not what it sounds - it is for the BBC, but it's not a plotter - it can more accurately be described as a tracer. It plots graphics onto the screen. It can work as a light pen, translating your free-hand sketches to the computer's memory. But it beats the light pen because it's also capable of tracing outline. If your drawing's like mine you'd rather lift someone else's artistic efforts in any case. It's ideal for copying maps or diagrams. Beebplotter can be used in any of the BBC's graphics modes and it plugs into the analogue port. It supports a number of commands to do things like fill enclosed spaces with a specified colour. The results can be dumped to a Seikosha or Epson printer and your efforts can obviously be saved to disk or tape. Contact Watford Electronics [redacted]. -- What about a system that accepts voice commands for the Apple II? VIM (Voice Input Module) represents a major advance in packaging what was previously mainframe experimental technique on a tiny card at a relatively tiny price (£899 inc VAT). The card disappears into the Apple and the only obvious bit of hardware is a microphone. You load up the requisite software and are ready to input. This is really a very sophisticated device as it scans the sound waves we offer it as input at several frequencies and samples them at specific points in time. You have to build up your own vocabulary of course, so that the thing knows what you're talking about. You type in a word and the system asks you to make the audio equivalent several times. Then it can get a good idea of how you are likely to say it. -- Micropaedia Editor: Geof Wheelwright Contributors: Ian Scales, John Lettice Design: Nigel Wingrove NEXT WEEK To finish off our series of buyer's guides we will be looking at a range of 'popular software' - otherwise known as games. Just in time for the Christmas rush, you can choose your stocking fillers from our selection of games for the Spectrum, Dragon, BBC, Oric, ZX81, Vic-20 and Atari.

Chatterbox starts from a slightly different premise from most units, in that it can be used for a number of machines with slight modification.

Mannesman Tally printers tend to be more upmarket, but the company does also sell the MT80, which is aimed more at the Epson end of the market.

Seikosha is best know in the hobbyist market for its low-cost printers. Print quality isn't as easy on the eye as more expensive models, but they're still excellent value.

The Currah Microspeech sells for £30, and while it's a reasonable little speech synthesiser in a crowded market, the really interesting things about it is that Currah is trying to get software manufacturers to incorporate its facilities into their games.

The Juki 6100 was something of an advance for daisywheel printers when it came out in the early Summer. At around £450 it brings the cost of letter quality daisywheel printers within striking distance of dot matrix. It's fairly good for the price, and importantly for daisywheel printers, is relatively quiet. Overall it's a highly creditable debut in the printer market for Juki.

The Prism VTX5000 modem for the Spectrum (top) is designed to hook the Spectrum up to Micronet 800. It's important because it's a cheap, hardwired modem that gives a mass market machine easy - and comprehenslble - access to the outside world in the form of Micronet and Prestel. Modems in general tend to be less accessible than this, but the idea is really that you can get your micro to talk to other micros over the phone.

Today when you say printer, you're very likely to be saying Epson. The Epson matrix printers are reliable workhorses in many an office and home.

Personal Computer Games

Tony Harrington

BOOSTERS Peripheral can boost your micro's powers and your fun. Tony Harrington has scoured the shops for you. There seems to be a new microcomputer on the market every week. But that is as nothing compared to the rich growth now taking place of computer peripherals of all kinds. You may want the freedom of a joystick for reflex-type games. Or you may want additional memory or processing power. In every case, there is bound to be at least half a dozen suppliers eager to offer their wares. The ideal way of doing a peripherals round-up is to group what is available for each brand of home computer. But many suppliers offer add-ons for more than one kind of micro, so the list becomes repetitive. In the first of our series of peripherals, therefore, we have listed the suppliers. The names of the micros are highlighted when the peripheral concerned is specific to a particular machine. First in our list is Flight Link, which is based in Alton. It makes three ranges of joystick, suitable for a wide range of micros. The first model in the range is the J1. This has dual axis carbon track controls and comes with or without cases, switches and cables. The second, JS2, has high-quality, all-metal dual controls. At the top end of the range, which will be outside the pocket of most micro-enthusiasts, is the JS4. It has inductively coupled contact less joysticks. This firm takes the business of making joysticks very seriously. It pays a lot of attention to unique demands, such as the control of puppets or the movement of vessels under water. Its products range in price from £3 to a staggering £1,000. Akhter Instruments, based in Harlow, also has a range of peripherals. In particular, there are three types of green monitors: the Hitachi MM1216 at £102.35; the SM12H 18MHZ monitor at the same price, and the cheaper,if less powerful SM12N 15MHZ at £79.35. All prices include VAT. The company also offers 14-inch colour monitors whose prices range from £239 plus VAT for the normal resolution of 400 dots up to £499 plus VAT for the high-resolution 800 dots screen. SIR Computers, from Cardiff, supplies a Z80 disk pack for the BBC Micro at £895. That sounds steep, but the system aims to be a sophisticated development of the machine's potential. It connects to the BBC micro in the same way as a normal disk drive. It then opens up the whole range of CP/M software for business and dataprocessing as well as games. This is because the firmware supplied with the machine allows you to switch between Basic and CPN, an operating system developed from CP/M 2.2. The disk pack also, of course, provides a dual 2 x 400K disk drive for use with the standard BBC Basic. The machine is able to run CP/M because it includes a Z80A processing card with its own 64K RAM card, which communicates with the 6502A in the BBC computer. The supplier claims that, in most cases, the speed of execution of programs is improved by up to 50% compared to conventional single processor computers. Computer Concepts has had considerable coverage for its Wordwise ROM-based word processor for the BBC micro. The price is £39 plus £1.50 for postage and packing; VAT is on top of that. The 'chip' plugs into one of the empty sockets inside the machine. It is supplied with a spiral-bound manual and a cassette which contains an example document and a free Typing Tutor program. Basingstoke supplier Fox Electronics offers the Vixen RAM cartridge for the Vic 20. This cartridge is switchable between 16K or 8K and 3K. It plugs into the rear expansion port and should be fully compatible with all motherboards and modules. No readdressing of existing Basic programs is needed. The price is £39.95. The same supplier also offers a 42-key travel keyboard for the Spectrum. You are supposed to be able to remove the ZX printed circuit board from your Spectrum and simply screw it down into the keyboard case. The supplier promises that no soldering is required. This costs £39.95, including postage and packing. There is also a ZX-Panda 16K RAM pack for the ZX81. This is expandable to 32K with a plug-in module from the same supplier. It includes a LED power indicator and is designed to connect without risk of the wobble that plagued the early Sinclair RAM packs. Prices range from £19.95 to £46.00 including postage and packing. For users who don't like the standard ZX81 keyboard there is a replacement keyboard with a calculator-type design. This is a stick-on replacement and is priced at £9.95 from Filesixty. Those of you who are being slowly blinded by the glare from your TV set being used as a monitor might like to try out the effects of antiglare screens. Merseyside firm Datatel Business Products offers a range of antiglare screens which give a sharper, clearer image and cut down eyestrain. The price is £19.95 plus £1.80 for postage and packing. Datatel Business Products also makes a multi-purpose computer stand which has an all-steel construction. This comes as a self-assembly kit and there are two sizes: two foot and two-and-a-half feet in height. KK Electronics, of London, has a range of colour monitors compatible with the BBC, Lynx, Oric, Acorn and all other computers with RGB. The monitors have a 16-colour display plus a brightness control. There is also a quality sound amplifier with loudspeaker control. Prices start at £239.95, plus VAT. A speaker which plugs into the microphone socket of the Spectrum and boosts the sound output is sold by Alan White, of Poole. The speaker comes complete with volume control and needs no soldering. It costs £5.50 inclusive of postage and packing. If you are worried about thieves making off with your home computer, you can at least ensure that they have to go to the trouble of taking the table with them, thanks to a little device from Ofco Ltd. Called Securit, the locking device fixes to the desk top without the need for any holes being drilled. It costs £29.95 plus VAT. More and more games designers are adding complex sound routines to their offerings. But for those Dragon owners who reckon that the sound of their machines still lacks a little, JCB Microsystems offers the Sound Extension Model for the Dragon 32. The price is £34.95 including VAT. The sound extension model looks much like an ordinary games cartridge and plugs into the Dragon's expansion port. Based on the AY-3-8910 sound chip, the module adds an extra command called music to Basic. The range of possible sounds is specified as numbers and characters. A sound synthesiser as used by professional musicians this is not. For the price, you wouldn't expect it to be. But it will produce a creditable set of tunes and a variety of games noises from wailing sirens to bomb blasts. The novice computer user will probably not have his (or her) machine long - and will run only a few programs - before the need for more memory becomes apparent. The BBC Model B, for example, has excellent ROM facilities, but has used up quite a bit of its RAM space accordingly. BBC Micro users after more storage will find the quaintly named Hobbit tape system worth a look. Made by Ikon Computer Products, the device operates as a sort of half-way house between cassette and disk-drive storage media. It comes in two parts: a cassette unit and an integrated circuit which contains the tape operating system to drive the Hobbit. This last comes as a ROM card which has to be inserted in one of the three sockets in the BBC before the cassette unit can be used. It represents a faster, more efficient and effective way of storing data and programs than conventional cassette recorders. And it has a number of commands which deal with the saving and loading of data. The Hobbit cassette unit is about three and a half inches wide, roughly the same in height, and four inches deep. It weighs two pounds. Four large rubber pads on the base ensure that the equipment stays on the table instead of skittering off onto the floor. The device has a data transfer speed of 750 bytes of data a second, five times faster than ordinary cassettes. The price is £135 plus VAT. Kempston Micro Electronics has a joystick named the Competition-Pro for the ZX Spectrum. It is a nylon and steel construction, with a self-centering stick and two fire buttons. It plugs into the Spectrum expansion port. You can buy it at WH Smith branches for £25 including VAT. The same supplier has joysticks for the VIC 20 and the Atari 400 and 800. They come at the somewhat cheaper price of £16.50 including VAT. Microcell Computer Systems, based in Leeds, advertises the Sinclair ZX 16K RAM pack at £28.50. The company also has a range of monitors including the BMC BM12E green monitor and the Sanyo SCM12H green monitor, both for £100. Cheetah Marketing, London, has an even cheaper ZX81 compatible RAM pack at £19.75 and the 64K RAM pack at £44.75. Both prices include VAT and postage and packing. Warrington firm Micro Aids has bought up a way of allowing keen Spectrum users to take their machines with them wherever they go. The Spectrum/ZX81 microcase is designed to hold the computer, power supply, printer and rampack, with space left over for a cassette recorder or the fabled Sinclair micro drives. The supplier advises that the shallow tray which contains the case can be used as an attractive desktop console. And the detachable top of the case could be used as a TV stand. The price starts at £29.95, including VAT. The Harrow-based firm, Home Entertainment Centre, has a number of add-ons for the Atari 400 and 800. In addition to joysticks at £14.95, there is a keyboard at £79.95, a 48K expansion at £99.95 and a disk drive at £289.99. If you have wanted to make your micro talk back, the Namal Supertalker is a useful extra. It comes from Namal Associates in Cambridge. Priced at £89.95, it has an extensive built-in ROM/RAM dictionary and a standard RS232 interface. It will run on a number of different micros. And as it is a phoneme synthesiser, it is not limited to particular words. It has been designed around the Votrax SC-01A phoneme speech synthesiser chip. You create words by using a sequence of codes to build words out of component sounds. Up to 200 to 250 new words can be dumped into the device's RAM to add to the 550 high-usage words already stored in ROM. Special versions are available for the ZX81 and the Spectrum. These versions are memory mapped. In compensation. the price for these two models is £49.95, including VAT.

Key. 1: ZX81 keyboard. 2: Atari disk drive. 3: Flight Link joystick 4: Sinclair 16K RAM pack. 5: Dragon 32 sound module. 6: BBC Hobbit storage unit. 7: BBC disk pack. 8: Kempston joystick. 9: Spectrum microcase. 10: Securit anti-theft device.

The Cheetah RAM pack.

The Flight Link joystick.

The Hobbit is a memory storage device for the BBC.

The Kempston joystick.

The Micro Aid case.

The Securit anti-theft device.

Personal Computer News

Len Warner

NAME: Namal Supertalker MANUFACTURER: Namal Associates, Cambridge [redacted] AVAILABLE: Mail Order, or from the Namal shop PRICE: RS232 £89.98, Spectrum £69.95, ZX81 £49.95 SOUNDS LIKE CHEAP AND CHEERFUL CHAT Len Warner puts words into the mouths of a number of micros with Supertalker from Namal. The Namal Supertalker is a very versatile speech unit on three counts. Phoneme synthesis gives it a flexible vocabulary, it has an extensive built-in dictionary ROM/RAM, and carries a standard RS232 interface. Currently it seems to be the only product in the lower price range which is not limited either by fixed vocabulary or to a single model of micro. The Supertalker uses an internal Z80 microprocessor to accept simple commands through the RS232 interface. This makes it easy to use, and allows it to be connected to most computers as if it were a serial printer. Two cheaper models for Sinclair ZX users have most of the features of the RS232 version. The sound comes from a small internal speaker driven by a 500 mW amplifier, giving ample volume for most purposes, while a jack lets you use an external speaker or amplifier for better quality sound or more volume. The Supertalker is designed around the Votrax SC-01. A phoneme speech synthesiser chip, which is effectively and electronic model of the human vocal tract. Words are pronounced by supplying the chip with a sequence of codes for the component sounds. For example, call' would be represented by the phonemes 'K-A W-L', or 'judge' by 'D-J-UH3-UH1-D-J" . The 23-page instruction book includes a seven-page article on the phonetic principles involved. It is the job of the Votrax chip to make the corresponding sounds and to blend together the word components smoothly, simulating the changes caused by muscular movements of the vocal tract. Vowel sounds glide between the consonants before and after them. This method has the advantage that any word can be spelled out in sounds, though it often requires a great deal of tinkering with different vowel sounds. At this point other low-cost phoneme synthesisers abandon the user to his own experiments. As you might imagine from the examples above, you can go bananas trying to teach your baby micro its first words. The Namal unit scores heavily here by having a vocabulary of about 550 useful words in a dictionary ROM. Each word can be spoken by giving its dictionary entry number. Word numbers can be strung together with phoneme codes to add endings to existing words, and there is space for 200-250 new words to be downloaded into the Supertalker RAM. This gently cases the user into coding new words . In use, it also keeps messages compact by storing them as sequences of dictionary numbers and provides for the unit to be set up for many different tasks. One other advantage is through the choice of the Votrax chip, rather than the more common and cheaper GIM SP0256. This allows the Supertalker a small range of voice tone inflection, and helps make messages more natural. The RS232 interface is designed for easy use. The connector is the readily-available 5-pin 180 degree DIN socket. An internal switch gives selection from 13 standard data rates between 50 and 9600 Baud, and choice of odd, even or no parity and one or twos top bits. Commands and messages are sent as standard ASCII characters. Handshaking can be either character 'A' returned to acknowledge data accepted, or the RS232 signal DTR held low when the buffer is full. This makes it compatible with a wide range of computer equipment, not just home micros. The Sinclair ZX81 and Spectrum versions are both memory-mapped and do not include their own Z80 processor. Instead, the Supertalker ROM contains a speech driver routine which is called by USR, and picks up a dictionary number previously POKEd into RAM. ZX81 Basic needs to be in Fast mode, or it causes unnaturally long pauses between words. ZX machine code programmers should have no problems, and lots of fun. New RAM dictionary entries can be built with a Basic program from the instruction manual, and PEEKing the ROM will provide lots of word coding examples. The Namal Supertalker clearly has a future with the discerning home computer user. Though the phoneme technique is not capable of Kenneth Kendall speech quality, it's often better than having to chop sections from a digitised speech ROM, with the jarring lapse in phrasing which results. It must also be a attractive to those with serious computer voice response projects in hand, but where cost is an important constraint. An example might be an aid for the blind or physically handicapped, where the Supertalker can speak a measurement, or verify a keyboard operation verbally. Instead of the available peripherals forcing your choice of computer, the Namal system leaves your options open. Schools and colleges often have a mix of computers, so they should find the flexibility of the RS232 interface helpful. A talking computer is also a great stimulus to student interest, especially when they can create new vocabulary.