Chatterbox

ZX Computing

Jim Watson

TALKBACK: SPEECH UNITS ASSESSED When you find you get to the stage where you find yourself talkiing to your micro, it helps if it answers back! From the time the Daleks trundled across our TV screens muttering "Exterminate, Exterminate" in their chillingly inhuman voice, I have been intrigued by speech synthesizers. At the time of writing, and to the best of my knowledge, there are six different units on the market to enable your micro to answer you back. Two others have recently lost their voice, I asked why, but the suppliers aren't talking. The units on the market at the moment are "Sweet Talker" from Cheetah for both ZX81 and Spectrum, "Micro Speech" from Currah, "Orator" from Fuller, "Vox Box" from Datel Electronics, "Chatterbox" by William Stuart Systems, and "S-Pack" by DCP. I contacted all of the above companies and those units that were supplied for review I sent to different reviewers for their independent comments. For your own assessment here's what they thought.... CHATTERBOX II William Stuart Systems [redacted] £39.00 + VAT Chatterbox II is quite a large unit - 10 x 15 x 6 cms - and is housed in a black plastic case which has two DIN sockets and a mini jack socket fitted on the top. The two DIN sockets allow you to connect the WSS Speech recognition unit (£49.00 +VAT) to one, and either the output from the WSS Music Synthesiser and 16 line control port (£19.50 Kit, 25.00 built, + VAT), or output to an amplifier to the other. The mini jack is an input from the Spectrum's ear socket to amplify its beeps. Compatible with BOTH ZX81 and Spectrum, it is attached by a cable and plug similar to that on the ZX printer, this means that though the port is OK for ZX81 peripherals, very few Spectrum units will fit on the back. Speech is achieved by using phonemes or individual speech sounds, and WSS themselves admit that the quality is not as good as preprogrammed speech, but add, and I see no reason to disagree, that the flexibility is infinite. A list of these phonemes is given in the 5 page booklet which is brief but reasonably clear providing you are an experienced user. To allow for connection to other machines a lot of technical detail is given, but unfortunately not how the INPUT/OUTPUT socket is wired so I couldn't try it with my Hi-Fi. To actually produce speech you have to break the word into its component sounds, look up the appropriate numbers and output them to port 127 using OUT 127, no. The quality of sound depends on the amount of time that you spend in getting the phonemes right, even at its best it still sounds electronic, but clear and recognisable. This will give hours of pleasure if you like tinkering, also it has great potential educational value as word structure has to be fully understood to get good results! Two complaints, first the loudspeaker is open at the front of the unit and could easily be damaged - surely it would not have been too hard to have covered it with a mesh or even cloth, and secondly there is no volume control. My family have banned me from using it when they're watching TV. Finally if you are a fan of Whizz Kids and admire the computer system used by them, then WSS go a long way towards providing a system with practical possibilities - fascinating!

C&VG (Computer & Video Games)

Robert Schifreen

EXTRA BITS! If you want to extend the capabilities of your computer or games machine there are now lots of bits and pieces which you can plug into the back to make it do things better or faster, or things which it could never do before. Such plug in goodies include extra memory, better keyboards, joystick interfaces, Micronet adaptor or devices to make the beast speak or play tunes. Robert Schifreen takes a break from Bug Hunting to bring you news of some of the current plastic boxes which you can plug into your micro or games machine. Upgrading your present equipment by using add-ons means that you may not have to buy that new machine after all! COMMUNICATIONS Communications means making your micro talk or listen to other computers in their own language. They communicate either over the airwaves at radio frequencies or over the telephone lines. Each has its advantages. Radio communication is only one-way whereas telephone can be both. But long conversations on the phone can be expensive. If you want to read more about this subject, dig out November's issue of C&VG and turn to page 114. If you want to receive Teletext on your micro, you'll need a BBC model B with a Teletext adaptor. This lets you receive Ceefax and Oracle, which are information services broadcast by the BBC and by ITV. You just plug your TV aerial into the back of the adaptor, and the computer will do the rest. The adaptor gives you four channels of teletext information; BBC 1, BBC2, ITV and Channel 4. You can find out about such things as what's on TV tonight, the latest world news, sports news and ITV also has a kids corner with jokes and the like. Teletext is like a big electronic newspaper, You can read its pages on your TV but you can't write back to it. The other method of communication is over the telephone. This is what systems like Micronet 800 use. This way, the computer can send messages and you can also type back. There are loads of computers which you can dial into and most of them are free except for the price of the phone call. However, these free bulletin boards, as they're called, run on different baud rates (no pun intended) to Micronet so unfortunately you can't use a Micronet adaptor to call them. You can buy a 300 baud modem quite cheaply from various companies, like Maplin Electronics who supply units for the Dragon, Vic-20, Commodore 64, Atari and Spectrum. I tested the Atari one and managed to dial into some local systems and also used Maplin's own service called Cashtel which allows you to order stuff from the Maplin catalogue via your computer by typing in your credit card number. A lot of computer clubs run bulletin boards, and you can dial them up for computing news; you can also send messages to the club by typing at your computer. This is the two-way advantage gained by using the 'phone as opposed to the airwaves. You can set up your own bulletin board with a Maplin modem, but you'll also need some software. You will soon be able to buy a Micronet/Prestel type modem for your BBC micro from Acorn which has some better features than the Micronet package. But it's more expensive, and you'll still have to pay a fee to join Micronet if you want to look at their private areas on the database. You can also buy slightly cheaper modems like the Micro-Myte which will not receive Micronet or other information systems, but will allow you to talk to your friend's computers, providing he or she also has a similar modem. This way you can send each other programs or messages, but you'll have to phone him up first to tell him to switch his modem on! The Micronet modems offer this person-to-person facility as well as normal Micronet use, but are slightly more expensive. STORAGE DEVICES When you finally decide that cassettes are too slow for your needs, you'll want to look for something faster. The best thing is a real disc drive which for micros will probably use 5.25" discs. A cheaper alternative is a 3" drive which is available for many micros. You can buy a Byte Drive 500 3" system from ITL for about £250, and this contains a special cable to link the drive to your micro. If you have two computers, or decide to change your machine, you just buy a new cable. Blank 5" discs start at about £1.50, but 3" systems use special cartridges which are currently about £6. The Byte Drive 500 will soon be available for the Dragon, Spectrum and Commodore 64. It is already available for the Oric, BBC and Apple. If you have a Spectrum, the official Sinclair way of progressing from cassette is the Microdrive. This costs £50 for each drive, but you'll also need an interface which is another £30. You can store between 85 and 100K on a Microdrive cartridge, and a 16K program will load in about 10 seconds. Microdrives are fast, but they're not really discs. Inside a microdrive cartridge is a loop of high quality tape, and the drive itself is just a very accurate (supposedly) cassette recorder. If you've got a BBC then you'll need a disc interface fitted, which costs around £90. ITL has no intention at the moment of producing one, so you'll have to use the BBC one. MORE MEMORY The size of the largest program which you cart fit into your machine is governed by the size of the area of memory in which the computer stores it. The problem is that although memory chips are now quite cheap, some micros still have very little RAM, as it's called. One of the first enhancements which a computer owner will make in such a case is a memory expansion. The ZX81 although very popular has only 1K of RAM. (1K is about two screenloads of program.) It's very easy to expand your ZX81's memory. You can buy a 16K RAM pack which just plugs into the back of the machine and costs around £30. You may have heard of the much-feared contemporary disease known as "RAM pack wobble", caused by Sinclair not putting the edge connector on their RAM pack in the right place. This disease can be fatal to a program, as a slight wobble at the wrong time can erase a whole afternoon's typing. One cure is a blob of something sticky under the machine, although a less messy solution is to look to a different company. You can also get 64K RAM packs which allow for even more storage of data and programs. Upgrades for the 16K Spectrum are available from Sinclair for £40, but you'll have to send your machine back to Clive, and you know how long that takes, don't you? Alternatively, you can buy a ZX81-like RAM pack which sits on the back of the machine, or some companies sell chips which you can stick inside, as long as you didn't really want the guarantee anyway. If you're going to upgrade your Spectrum, check that the company's product will fit your particular machine. There are currently three different versions of the Spectrum in circulation and although they all look the same from the outside, there are some small variations inside which may make a difference. Expansion for an Atari is easy; the memory comes in chunks of plastic which you install by removing the cover on top of the machine. Newer machines come with 48K but some old 400's still have only 16K. Your local dealer should be able to tell you how to improve this. To expand a Texas TI99/4 or 4a you'll need a peripheral expansion box. This takes the form of a large aluminium crate about the size of the small freezer compartment in a fridge. (I don't know why, but everyone seems to measure the size of computers in relation to parts of fridges.) Inside this you can then put disc drives, memory expansions and anything else. Retail price for the box alone was around £80 but that may drop now that the Texas micro is no longer being made. Memory expansion on a Vic is peculiar. It is in the form of plug-in cartridges and comes in four flavours, which are 3K, 8K, 16K or 32K. The annoying thing is that because the cartridge overwrites that part of memory which used to hold the contents of the screen, the screen RAM is moved to a different place. The problem is that each cartridge puts it somewhere different, so programs written for use with an extra 3K will not necessarily run directly on a 16K machine without minor alterations. This is very inconvenient, especially for magazines who publish program listings! If you're tired of having to do octopus impressions to play your favourite computer game a joystick interface is called for. This allows machines which normally have no provision for such a gadget to have one, and very useful they are too. The most popular machine, which lacks a joystick interface, is the Spectrum, and there are now quite a few companies who will remedy this situation for you. The official way is by use of the Sinclair Interface 2. This costs just under £20 - you get 5p change! - and allows two standard Atari-type controllers to be used. You can then write your own games using the joysticks to control the action, or buy commercial software written for use with the device. Interface 2 also allows you to use plug-in cartridge software, although these retail at £15 a time. The problem with all the different joystick interfaces is that they use their own systems. So a program written for use with a Kempston joystick will not run on an Interface 2 unless the program contains a routine for each and you are allowed to select which one you want. One way round this predicament is by a programmable joystick interface. Such a beast is the one from AGF. This comes with a grid of small holes and a set of five wires. The wires are labelled with the functions of the joystick (up, down, left, right and fire) and the holes are labelled with the keys on a Spectrum keyboard. If the game which you want to play uses the 'K' key to fire, then you plug the 'FIRE' lead into the 'K' hole and so on. Such a device is very useful. BETTER KEYBOARDS When you finally tire of the piece of dead flesh known as your Spectrum's keyboard, there are a number of better ones around. The best are quite expensive at around £40 but they allow the whole machine to fit inside and look rather smart. One of the most popular around is made by Fuller. Kempston is also about to launch a high quality keyboard for the Spectrum, as demonstrated recently at the ZX Microfair. You'll also find replacements for the touch-sensitive keyboard of the Atari 400 from about £65. If you have an Atari VCS and feel like getting into computing, you can now buy an add-on keyboard from Vulcan Electronics, which is made by Spectravideo. It sits on top of the VCS and plugs in to the joystick ports and the main cartridge slot and you can then program your VCS in Basic, it costs £50. Mattel Intellivision owners can also do the same to their machine. Mattel offers a similar device, as well as a music keyboard to enable you to compose music on your machine. I don't reckon Bach would think much of it, but it's not bad. SOUNDS AND SPEECH If your idea of a good evening is being locked in a quiet room with a micro, then you could always get more friendly with it by talking to it or having it talk to you. But before those nice little men in white coats come to take you away, let me explain. If you have a Pet, Vic, 64. Spectrum, ZX81 or BBC and need someone to talk to you then you could always try a Chatterbox. This costs £49 from William Stuart Systems and you can program it to say anything you like. From the same company comes Big Ears which, for another £49, reverses the process and allows you to speak to your computer. Say the word through the microphone a few times, and the machine will then remember it. If you then say it again, it should recognise what you're saying. If it's a Spectrum you've got then the Currah Microspeech is another possibility besides a Chatterbox. It works on the same system and sells for under £30. BBC owners can also choose the official Acorn speech system, which is a computerised version of Kenneth Kendall. Personally I can just about recognise him, but many say that it might just as well be Moira Stuart. (In fact, I wish it was.) If you prefer noise to plain speech then there are a couple of units available to improve the sound of a Spectrum by providing it with the same sound chip as the BBC and Oric. WHAT'S LEFT OVER Finally, we come to the rest of the oddments which space did not allow separate headings for. If you own an Aquarius, then this year should see the introduction of the home controller unit. Th is plugs into the machine and allows you to control household appliances by using special plugs which go into the wall and receive messages from the computer. Such a system is also planned for the Electron. If you have an Atari VCS then you may already know about the super expander. This lets you load games from cassette, and also improves the quality of the graphics slightly. Printerface is a mixture of interface and printer and is a device to let you link a printer to a micro. DAMS office systems supplies an IEEE cartridge to allow a Vic or 64 to connect to any Commodore printer (or disc drive for that matter.) The Spectrum will only work with a ZX printer, but you can use the RS232 connection on an Interface 1 to link a large range of printers. If you have a Centronics-type printer then Kempston will supply you with a suitable interface for a Spectrum. If you own a computer other than a Sinclair machine but would be perfectly happy to use a cheap (£40) Sinclair printer, you can get a suitable interface for many popular micros, including the BBC, Dragon and Vic, from Microtanic Computer Systems of London. LIGHT SENSORS Another way of controlling a game is with a light sensing device. Usually mounted in a pen-like barrel (and, therefore, called a light pen) these allow you to draw patterns on the screen as though it were a piece of paper. Recently launched is the Light Rifle from Stack Systems of Bootle, Merseyside. It comes with three demo games where you have to shoot at targets on screen, just like those old TV game machines, but these games are better as they rely on all the facilities of the micro. You can also write your own shooting-time programs. The light rifle costs just under £30 and versions are available for the Spectrum, Vic and 64.

At long last, the microdrive has actually been launched. As expected, demand is still exceeding supply and it will be some time before you can just walk into Smiths and buy one. They're not really disc drives at all, just miniature cassette recorders. You can load a 16K program from a Microdrive in about 10 seconds.

The byte-drive 500 is a 3" disc drive from ITL. The small discs are enclosed in rigid plastic and currently cost over £5 each. The clever part is the cable which links the drive to the micro. This contains all the electronics, so if you change micros, you just change the cable but keep the same drive.

You can now fit two standard Atari-type joysticks to your Spectrum with an Interface 2. It plugs into the back of the computer, and also has a slot to take the new Sinclair software cartridges. The BBC (below) can now become a Teletext terminal with the new add-on from Acorn. As well as displaying pages of information, it can also store the data in memory and use it in its own programs.

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 News

John Lettice

ITEM: Big Ears PRICES: £49 MACHINE: Various CONTACT: William Stuart Systems, [redacted] MICROS HAVE EARS You can talk to your Spectrum, but you won't get a reply - John Lettice looks at Big Ears. Speech is still something of a new frontier as far as the cheaper micros are concerned. The problems that must be solved are complex, but some of the tools you need are now available. PCN looks at a duo from William Stuart Systems. Speech synthesisers are now so common that the world and his wife's micro seem to have access to them. In the case of mass-market micros like the Spectrum, the range is so wide that users will encounter considerable difficulty making a choice. Assuming one Dalek sounds pretty much like another, you may think that making a choice is simply a matter of the convenience and prices of the various pieces of hardware. But when you think about the sort of things you'll want to use a speech add-on set-up for, you'll realise that there are other considerations. Speech synthesis at the low-end micro level has been conquered to all intents and purposes, but the problem of cheap speech recognition still remains. Wouldn't you like to have full verbal control over your micro, with all that implies for control of peripherals? For example, you could stand in the middle of the room bossing a turtle around - and at the really gosh-wow end of the market, you could phone up your ZX81 and tell it to switch on the video recorder. Interested? Well, the good news is that it can be done - the bad news is that it can't. The reason things are a bit equivocal at the moment is that, while the hardware that makes possible the solution to the problem exists, the software to make it work still has some way to go. For example, William Stuart Systems is currently marketing a speech synthesis unit called Chatterbox, and a speech recognition unit called Big Ears for £49 each, giving you the necessary hardware to - in theory at least - produce a very cheap speech system. Compare the price with the £899 for the Apple Voice Input Module (PCN, issue 15) and you'll naturally assume there's a snag. Well there is - Big Ears will recognise your speech quite effectively, but you'll have grave difficulties getting it to produce more than demonstration speech output, because you'll either have to write your own software, or wait. PRESENTATION Big Ears can be connected to a wide range of micros through the Chatterbox speech synthesiser or through a number of commercially available input/output ports. The test model was run on a ZX Spectrum through the Chatterbox, and came with a microphone, lead and driver/demo software tapes. We tested it with Chatterbox 1, which can be upgraded to Chatterbox 2 for £5.75. The whole ensemble came in a tidily packed box, complete with copious quantities of instruction leaflets. DOCUMENTATION The presentation of the instruction leaflets is, to put it mildly, a shade on the rudimentary side. Chatterbox is well documented, but the main manual for Big Bars (15 pages of stapled A5) seems to spend most of its time on the UK101 and Nascom. Along with the main manual you get two sheets of A4 giving supplementary information for the Spectrum and ZX81. If you're running Big Ears off a ZX81, the POKES you need are given, but the rest of the machine-specific information seems to be just a variant on the Nascom/101 instructions IN USE Getting the whole set-up running was relatively easy. You plug Chatterbox into the Sinclair's edge connector, connect it up to Big Ears, plug the microphone into Big Ears, power up and you're away. Load up the Big Ears software, and you can begin teaching your micro to recognise words. You're initially asked whether you want to 'learn, test, demo or save'. Your first move, logically, is to select '1', which allows you to place a word in the machine's vocabulary. Each new word should be assigned a word number, and then the word itself is typed in. You then press Enter and say the word, four times, by which time the Spectrum has a fair idea what you're on about Once you've got a couple of words stored - with the software supplied the maximum is ten - you can test Big Ears' recognition capabilities. At first I had problems here - I'd hit t, then Enter, and as I was gathering breath to say something, 'You said pig' would flash up on the screen. The manual was silent on this subject, and the main manual itself gives the impression that you'll get a 'Please speak ... Now!' prompt before having to open your mouth. However, I tried bellowing at it the moment I'd entered 't', and found I got the required attention. The recognition seems quite good for one voice, but when we tried varying the voices it learned from, it showed a tendency to confuse Igor and pop If as is very likely you find you need to store more words, instructions are given on how to alter the program to increase its capacity. You can also vary the number of repetitions needed for the program to store a word, bearing in mind that the more repetitions, the better the recognition. Round about this point you'll start wondering what you could get it to do next, and how. Big Ears stores words as a sort of digitised voiceprint, and you can see this as you teach it words, should you wish. But Chatterbox, and most other cheap speech synthesisers, work on an allophone system, allophones being units of sound that human speech is made up of. The problem is turning your voiceprints into something that the Chatterbox can reproduce in allophone form if, that is, you want to be able to talk to Big Bars and have Chatterbox repeat your words. But note that this is not the same as Big Ears understanding you. What you need to make the device of more immediate use is the software to allow it not simply to repeat words but to act on them. Now, provided you can produce a stable enough sound, and back it up with software that will recognise the 'print' of that sound - obviously not an exact print, but one within a given margin of error - you could get your micro to execute an action. As the demonstration software included with Big Ears allows you to alter the number of repetitions the device demands before it 'learns' a sound, and as the more you do the more accurate it is, you can probably nail its print down fairly tightly, and bear in mind you don't have to stick to sounds you make with your larynx. No, don't go away... if what you want is a series of simple actions, why not try clapping, a knock on the desk, whistling? Why not be the first on your block to have a micro that dims the lights every time you clear your throat?. VERDICT The potential for Big Ears is clear, but unfortunately it's still largely unexplored. William Stuart Systems is currently working on applications software for the Spectrum, and UK101 software is probably a little further advanced, but the company says that, because users will tend to want to employ Big Ears for specific applications, it's very difficult to decide what sort of routines to include. So, really, what you're talking about here is a product that needs a fair bit of programming input before you can use it to its full potential, and if you want to control your environment by voice, you'll also need to be pretty nifty with a soldering iron. But this isn't a complete disqualification for novices. If you're willing to teach yourself, and if you're clear in your mind that it will take you some time to get the results you want out of Big Ears, then it does represent excellent value for money.

The complete set-up - Big Ears, top left, is linked up to the Spectrum through Chatterbox. Jut speak into the mike and your voiceprint appears on the screen.

The inside of Big Ears consists mainly of a commodious voicebox.

TWO-WAY COMPUTER COMMUNICATION The Chatterbox - also known, as you can see, as Speech Synthesis by William Stuart Systems - will connect direct to your micro to provide an allophone base speech synthesis. Speech recognition - nom de guerre Big Ears - links up through the Chatterbox, and renders your speech into easily recognisable voiceprints. Allophones may take a little longer.

ZX Computing

ADDING ON YOUR SPECTRUM Our review team take a brief look at some of the hardware add-ons fir the ZX Spectrum. Now that the ZX Spectrum has well and truly established itself on the micro market, it is amply supported by a wealth of hardware add-ons. Most of these peripheral devices have been manufactured by the people who supported the ZX81, but just as the Spectrum has attracted new users with its prowess, so too has it attracted a new following from the add-on manufacturers. In this brief guide, we have not tried to cover all the devices currently available on the market but rather give you a flavour of the technology you can add on to your Spectrum. As joysticks are an obvious favourite, these have been covered in some detail whereas RAM packs are fairly standard and so have only been briefly touched on. Also included in this section area number of quite specialised add-ons like sound units and a digital tracer. If you own a Spectrum, you will no doubt have begun to realise the potential you hold in your hands. Over the next few pages you will hopefully see further applications for you and your computer to explore. CHATTERBOX - WILLIAM STUART SYSTEMS Chatterbox uses a novel method of forming speech - it does not contain a fixed vocabulary, but rather depends on the building up of individual sounds (or phonemes) under program control. The Chatterbox itself is a nice solid box with a speaker unit built into the front. The output from the speaker is clear and set at a reasonable volume. There is also a speaker output at the back of the unit, as well as an audio output which could be played through your hi-fi. The Chatterbox is connected to the rear edge connector of the Spectrum and provides room for additional hardware to be added on. The speech output from the unit is of quite high standard and is certainly fun to play with. By POKEing various codes, it is possible to build up words by their basic sounds. It sounds fairly easy, but it can take quite some time to find exactly the right sounds you need before anyone can recognise what you are trying to say. It is a triumphant moment though, when your Chatterbox finally puts together its first word. The unit comes complete with a list of codes with which to experiment with and use as building blocks, as well as some program examples of how to utilise the device within your programs. The Chatterbox is priced at £49 or £39 as a DIY kit. For further details contact William Stuart Systems Ltd, [redacted].

The Chatterbox speech synthesis unit from William Stuart Systems.