PRINT A PRINT

If you ever wanted a permanent record of listings or screen printouts, you may have considered a low-cost printer. Up until recently your choice would have been confined to the Sinclair ZX printer. At £39.95 it certainly proves to be the cheapest on the market, but unfortunately it has also received the longest list of not too kindly and often unprintable nicknames from its harassed users. Complaints on paper running askew, feed slippage, lack of print quality due to low-grade silver paper, etc. have not endeared it even to the most ardent Sinclair fans...

Rescue has come from DEAN Electronics, who introduced the ALPHACOM 32 printer for the ZX Spectrum (and the ZX81) in this country. This unit has been developed in the States as a sturdier alternative to the original Sinclair printer, which is not being marketed there. Anybody with a dislike to the ZX printers silver paper may be pleased to note that the ALPHACOM 32 uses normal white thermal paper. The result is very readable. The only problem encountered with the print quality is that photocopying is very difficult, as most photocopiers are insensitive to the blue printout.

GETTING STARTED

The unit comes in a rather large polystyrene box and includes the printer with its edge socket and cable, a hefty power supply, a roll of paper and an instruction sheet. With all power plugs removed, the printer's edge socket is connected to the Spectrum. The edge socket is a 23-way edge connector and will fit the ZX81 and Spectrum edge connection. An extension port is provided at the rear of this socket, which is suitable for the ZX81 add-ons, but not the Spectrum add-ons, since these use the 28-way edge connector. This means that the printer should be connected at the end of the line of add-ons and no problems will be encountered unless one of the add-ons does not have an extension port.

The printer receives its power from its own power source, which generates 24V AC. A line jack-plug connection is provided between the two units for powering up the printer. Once connected, pressing the ON/ADVANCE button will start up the printer ready for loading paper or printing. The ON/ADVANCE and OFF switches on the printer do not physically connect or disconnect the printer from the supply line and it is therefore necessary to disconnect the printer from the power supply with the jack-plug connectors for longer shut down periods.

LOADING PAPER

The printer uses standard thermographic printing paper of 4.25" x 1.9" diameter. The clear acrylic receptacle cover hinges open and the paper roll placed into the paper tray is fed with about six inches protruding from underneath the roll below the rubber platen while pressing the ON/ADVANCE button. The paper should feed automatically. It is best to have a clean-cut leading edge, so that the rubber platen can get a good grip. Pulling the leading edge towards the front, the cover may be closed. If ON/ADVANCE feeds the paper correctly, the printer is ready for action. The printing action may be checked with the in-built self-test mode, which prints a line of eights and a line of ones.

SILENT RUNNING

The printer operates with very little noise. Printing speed is similar to the ZX printer, possibly a fraction faster and definitely more regular, as the asthmatic ZX printer usually runs out of breath when negotiating long listings. The print quality is better than with the ZX printer. The horizontal dot positioning is far more accurate, as each thermal head only has to scan eight horizontal dots. The ZX printer on the other hand has a set of conductive styli running along the entire width of the paper and their position is monitored by a signal generated from the stylus hitting the leading edge of the paper and from an optical encoder disc, so positioning errors may occur and accumulate over the 256 dot stretch of the print run. The paper feed works well; no paper running askew or slipping to create foreshortened characters. The ON/ADVANCE and OFF facility proves useful with software, which includes unconditional print commands, as the print action can be switched manually on or off without going to the trouble of disconnecting the printer from the Spectrum.

APPLICATIONS

When buying a printer it is necessary to consider precisely what it is required to do. If you require word processing on the Spectrum, then obviously the ALPHACOM 32 is totally the Spectrum, then obviously the ALPHACOM 32 is totally unsuited for this application. Nothing less than an 80 character width daisy wheel printer and a proper typewriter-style keyboard should be considered and this means running up costs of over five times the value of the ALPHACOM 32. If, on the other hand, you require a machine capable of creating program listings, or making screen copies of title pictures or technical/financial graphs, then the ALPHACOM fits the bill. The listings are very legible and are a godsend for debugging long programs without eye strain. The screen copies are an added bonus, but it is a shame that the paper feed is just that little bit too fast and creates unnecessary white gaps between the screen plot lines and elongates the vertical dimension of the screen picture.

Many Spectrums find their way into development or test laboratories as cheap scientific calculators and a hard copy is always required. With very little extra hardware (PIO and A/D extension cards) the Spectrum can operate as an intelligent measuring device or datalogger and can even replace an expensive chart recorder.

CONCLUSION

The ALPHACOM 32 is an ideal and dependable printer for program listings, screen copies and any other applications not requiring large paper format. For those people who do not want to be bothered with the unorthodox silver paper and the dodgy feed of the ZX printer, it is well worth the extra cost of the ALPHACOM 32.

STANDING IN FOR THE SINCLAIR PRINTER

Dean Electronics has announced the introduction of a Sinclair-compatible thermal printer, the Alphacom 32. It is manufactured by the American company which produces the Timex-Sinclair 2040 printer - reviewed in the July Sinclair User. The printer is very different from the U.K. Sinclair printer in both external appearance and print quality but is designed to be just as easy to use. It plugs into the rear connector of either a ZX-81 or Spectrum and will accept the standard commands of LPRINT, LLIST and COPY.

That means it can be used in exactly the same manner as the Sinclair, without alteration to existing software. Using 110mm. wide white thermal paper, it produces a very readable output at a speed of roughly two lines per second.

The printer casing is approximately 195 x 140 x 55mm., black-moulded ABS, with a perspex blister on top which holds the paper. Two thick wires emerge from the back, one about 150mm. long to the edge connector which has a ZX-81-size connector to the computer and a through port for RAM packs and the other to the supplied external power supply by way of a male 3.5mm. jack plug.

Inside the printer there is a minimum of electronics, a ROM chip to handle the printer operations, five chips to control the printing mechanism, a handful of discrete components and two PCB-mounted switches to turn the printer on and off and to advance the paper; the use of both switches together performs a self-test function.

The bulk of the space is taken up with a very solid-looking, rubber-mounted, printer mechanism. The mechanism contains, to one side, a 1 5V motor which, through a series of nylon gears, turns the rubber platen which feeds the paper through and also moves the printhead.

The print head is made of a ceramic material into which are inlaid 20 wires. As they are moved across the paper they burn off the top surface of the paper to leave a black ink impression.

Each wire covers two character squares in a zig-zag fashion which shows up the only disadvantage of the printer. When producing a copy this zig-zag is noticeable on any solid blocks of ink.

The printer becomes warm in use but that is not a problem as there are adequate ventilation slots on the top and bottom and a large heat-sink inside.

One slight problem, however, is that on a Spectrum the edge connector lead fouls the power lead, making insertion difficult.

Priced at £59.95, including power supply and one roll of paper, with extra rolls of paper at only £1, the printer must be seen as a viable alternative to the Sinclair printer.

The Alphacom 32 is obtainable from Dean Electronics Ltd, Glendale Park, Fernbank Road, Ascot, Berkshire SL5 8JB and branches of W H Smith.

GETTING INTO PRINT

The decision to buy a printer to complete your computer system will be one of the most difficult and certainly one of the most expensive which you as a Sinclair user will have to make. The variety of printers available tends to confuse rather than facilitate your choice and many of them are likely to cost than the rest of your system.

Yet if your are intending to use a Sinclair machine for something other than games playing, you will, sooner or later, need to make a permanent copy on paper. With that in mind Sinclair User looks at 11 printers, from the inexpensive to those suitable for small business.

The first consideration must be the purpose for which you intend to use a printer. All the printers reviewed will produce listings of programs, some faster than others and some more legibly. If you intend to do some word processing the type-style and method of printing is also important.

Most of the machines reviewed are dot matrix printers. That means that, just as characters on the screen are composed of a number of dots - pixels - the printer has a number of little pins which are pushed on to the paper, through the ribbon, to form the character. The greater the number of dots the better the definition of the character.

Just as user-defined graphics are made by changing the arrangement of the dots, dot matrix printers can easily change the type-style or the character. The printer holds those definitions in ROM and by telling it which set you want to use it can print in different type-styles and use different national characters, in some cases even Japanese.

Some of the printers use different methods. The Alphacom 32 and the Brother EP44 are thermal printers. That means they use special, more expensive paper although they are still dot matrix types. The pins become hot and cause the paper to change colour. The Brother can also use plain paper with the addition of a special ribbon.

The Dyneer DW16 is a daisywheel printer, using a wheel which has each character, like those on a typewriter, at the end of a spoke. To change type-styles the wheel has to be changed.

The Olivetti JP101 has a small cartridge which fires an ink-jet at the paper. As there are few mechanical parts the printer is quieter than most.

The Tandy CGP-115 has four ball-point pens which form characters by moving the pen horizontally and the paper up and down.

The speed of a printer normally is measured in characters per second; in theory the higher the number the greater the speed. To test that we used a standard body of text, the first chapter of Genesis, and timed how long it needed to print. The text was prepared using Tasword 2 and printed via a Kempston E interface, where suitable, a total of 796 words over 77 lines.

The results were surprising. The Microline 80, with a quoted speed of 80 cps, took nearly twice as long as the Mannesmann Tally MT80 and three times as long as the Olivetti. The answer would be to take such quoted figures only as a very rough guide.

Another thing to consider is how you want to drive the printer. Two of the machines reviewed connect directly to a Sinclair computer, the Alphacom 32 and the Seikosha. While that is undoubtedly the cheapest method, when and if you upgrade your computer you are left with a printer you may not be able to connect to your new machine.

There are two standards by which printers normally are driven, Centronics and RS232. Roughly speaking, Centronics interfaces have eight wires so that the bits of each byte travel to the printer at the same time along each wire. Serial interfaces have one wire and the bits travel along it one after the other.

Whether you use Centronics or RS232 does not make much difference so long as you do not try to mix them. On many of the printers Centronics is fitted as standard and RS232 is available as an add-on at extra cost.

Your future plans must be taken into consideration. Users with a Microdrive can use the RS232 port fitted. If you are thinking of buying a QL it also has an RS232 port fitted as standard. Other add-ons such as modems also tend to use RS232 and so the system has advantages, despite the extra cost.

The width of paper the printer can handle may also be a consideration. Normal listings may use only 32 columns but if you like to add REM statements at the side or for word processing, 80 is the minimum.

It is often necessary to indicate to the printer what you want it to do, whether changing the type-style or feeding paper through it. There is a standard for it known as ESCape codes, i.e., codes which escape from normal printing to do something different. Those codes were originated by Epson and are now used by most other makes of printer.

To help you each printer is now considered, briefly, in turn. The Sinclair printer has not been included as it has been discontinued and will be available only while stocks last.

Alphacom 32 is the cheapest on the market at the moment. It has reasonable print quality and is easy to use. It has only a ZX-81 size connector, so Spectrum users must use it as the last add-on. From Dean Electronics or Prism.

Seikosha GP50S is an inexpensive plain-paper printer, not particularly fast and rather noisy but easy to use. It has a Spectrum-size edge connector, so ZX-81 users will need an extender card not yet available from Seikosha, so try Eprom Services. From Dean Electronics or Prism.

Tandy CGP-115 is the cheapest colour printer; it is very slow but can do pleasant graphics with the appropriate software. From retail shops.

Microline 80 is supplied with roll paper holder as standard. It uses ordinary typewriter ribbons. It has only one type-style. From X-Data.

Brother EP44 is a portable typewriter with RS232 connection. It is not really suitable as a computer printer but as a typewriter it is amazing. From local typewriter shops.

Olivetti JP101 is a quiet ink-jet printer; it has slightly blurred print but is reasonably fast.

Epson RX80 is the standard by which other printers are measured. It is versatile with clear print and all the facilities you are liable to need.

Star Gemini-10X was caught by a recent price reduction for the Epson which it mirrors. It may be discounted further. From London Computer Centre or Micro Peripherals.

Mannesmann Tally MT80 is a good looking printer, also heavily discounted.

Canon PW1080A is very fast and has a good range of facilities, including programmable characters. It is slower in near letter-quality mode. From London Computer Centre or Micro Peripherals.

Dyneer DW16 is a business users' daisywheel printer. The code is compatable with Diablo printers. From X-Data.

British Olivetti Ltd, 86-88 Upper Richmond Road, London SW15 2UR.

Dean Electronics Ltd, Glendale Park, Fernbank Road, Ascot, Berkshire SL5 8JB.

DRG Business Systems Ltd, Peripheral Division. 29 Lynx Crescent, Winterstoke Road, Weston-super-Mare. Avon BS24 9DN.

London Computer Centre, Grafton Way, London N1.

Mannesmann Tally Ltd, Molly Millar Lane, Wokingham, Berkshire, RG11 2QT.

Micro Peripherals Ltd, Basing, Basingstoke, Hampshire RG24 0BY.

Prism Microproducts Ltd, 18-29 Mora Street, City Road. London EC1.

X-Data Ltd, 750-751 Deal Avenue, Slough Trading Estate, Slough, Berkshire SL1 4SH.

RISING THERMALS

Until recently the only printer which would connect straight to a ZX81 or Spectrum without extra hardware was the official Sinclair electrostatic printer. Currently priced at £39, it's still pretty good as value goes. Problem is that it doesn't go very far where print quality is concerned. The paper's also quite expensive and is difficult to write on.

Without opting for the expense of a professional dot matrix or daisywheel printer, there is still a happy medium to be found (Russell Grant take note) in thermal printers. These use special paper, but it's treated in a different way. It's a lot thinner, and you can write on it too. Rolls of this thermal paper cost around £l each and, because it's thinner, you get a lot more on a roll.

There are two thermal models, distributed by Dean Electronics. Called the Alphacom 42 and 32. they cost £99.95 and £59.95 respectively.

The 32 will plug straight into a Spectrum or ZX81 and print the full graphics of the machine. As well as being easier to read than the output from Sinclair's device, it also prints faster.

The model 42 comes complete with an interface to link the printer to an Atari, Vic, 64, Dragon or BBC and prints all the graphics. Further interfaces can be plugged in and they cost £25 each. So if you've got a Beeb and a Dragon, you can link them both to the printer for a total of under £125. The Commodore version works with both the Vic and the 64, and even prints cursor control characters properly.

A couple more Commodore add-ons have arrived recently. Protek has brought out an interface which will allow you to use any tape recorder with your Vic or 64 - you won't have to fork out for the overpriced Commodore version. This box of tricks cost £9.95, and Protek is based in Edinburgh,

Ray Elder takes a look at another way of getting into print at a reasonable price.

The first attempt to improve the listings in ZX COMPUTING was an investigation into an alternative printer. The Alphacom 32 is the American version of the Sinclair printer and is marketed in Britain by Dean Electronics. Originally priced at £99.95, it has now been reduced to £59.95 due to an exclusive distribution agreement.

In size it is nearly twice as deep and slightly longer than the ZX printer and looks an altogether sturdier machine (actual measurements are 19.4cm x 14.4cm x 7.5cm). The printer comes complete with connector, a roll of paper, instruction book and power supply unit, the PSU being used at the same time as the Sinclair PSU. It also uses all the Sinclair commands; LLIST, LPRINT and COPY.

Having unpacked the unit from its attractive box and read the instructions, the next thing to do was connect it to the Spectrum (it is compatible with both ZX81 and Spectrum). The Alphacom connector is larger than the usual connector, having a hump which is flush with the top of the Spectrum when fitted, and a row of spring clips along the underside. These clips do not seem to have any practical use (probably an earthing connection on the American Timex machine) but you have to fit the connector carefully in order not to bend or break them. The connector has a good, tight fit and presented no problems.

Next step was to fit the paper to the machine. Thermal paper is used as on the ZX printer, but this is white unlike Sinclair's silver paper, and it produces a blue coloured print. Feeding the paper into the machine only took a few seconds and the roll then sits in a tray. It is not held on spindles like the Sinclair roll and this probably helps to keep the feed straight.

Two switches are provided on the printer, an OFF and an ON/ADVANCE switch - pressing both puts the printer into self test mode where it continually prints alternate lines 1s and 8s.

OK, so what's it like in operation?

The first thing I noticed was how quiet it was. Being used to the ZX's strangulated croak, I was worried that it wasn't working! But, as the print appeared the other immediately impressive feature became obvious - the speed of printing is much faster, two lines a second in fact.

For technical buffs I'll give the specifications:

Graphics at 80 dpi (256 x n)
Vertical line spacing; 6 1pi
Horizontal spacing: 10 cpi

For non technical buffs, this means that the print is slightly thinner and slightly taller!

The print is easy to read with the naked eye, looks very professional and the paper is easy to handle. It does not tend to take a copy of your fingerprints every time you touch it! The paper is also much cheaper than the ZX printer paper, at £1.00 per 25 metre roll.

The main disadvantage of this machine is the great number of extra leads involved by using a separate PSU. If your system is permanently set up then they can be tucked away neatly and forgotten, but if you are using a mobile system then they add significantly to the spaghettiness of the situation.

Having produced twenty or so printouts on this machine, I sent them to our reproduction department for them to congratulate me on discovering a better listing print. My smug self-satisfaction was quickly destroyed as the print would not copy well enough to use in magazine! The project therefore, is still on.

However, if you are looking for a very good alternative to the ZX printer, I can wholeheartedly recommend this machine. At the new reduced price it represents very good value for money.

Fig. 1. shows a few lines from this printer as an example of its output. Please remember that the reproduction is not very successful and the quality is actually better than is shown.

Finally, Dean Electronics can be contacted at Glendale Park, Fernbank Road, Ascot, Berkshire, SL5 8JB. Meanwhile, they have kindly donated an Alphacom 32 as this month's super competition prize.

HOTHEADS

If you're not that flush, but you need a printer, stay cool and go thermal. Peter Green comes in from the cold to consider the hottest ones around.

The Sinclair ZX Printer was unique - for its size and price, it was quite a remarkable technical achievement. Still, it did leave something to be desired. All those sweaty paw prints, left all over the silver listing paper. And the print quality would strain the definition of the word adequate, as well as your eyes. Program listings on the stuff cause harassed editors to tear their hair out (or at least that's Kevin's excuse!).

One solution has been to find a way of linking 'real' printers, like the large dot matrix ones, to your Spectrum. For that you need a commercial interface, or you could have a crack at knocking up one yourself. (Of course, you'll need a copy of YS issue 6 for that. Ed).

This works, but your Speccy is now dwarfed by a huge printer - a bit of a shame when Uncle Clive has gone to so much trouble to keep it all small. And it causes even more problems if you've got to squeeze your complete computer setup into the confines of a cramped living room - worst of all it means shelling out between two and three times as much for the printer as you paid for your Speccy. That's good enough reason for me to look seriously at thermal printers.

ANYTHING YOU CAN DO...

So, what can thermal printers do that dot matrix or daisywheel can't? Well, nothing really - except save you a lot of space and some cash. Most of them are quite tiny, and the good news is that they're all comparable in price to a Spectrum.

Thermal printers don't need linked ribbon because they use special paper impregnated with a heat-sensitive ink. The print head is still 'dot-matrix' but the dots are small wires that can be independently heated. The heat makes the ink visible in the correct dot patterns to display characters. Take into account that the saving you'll make on ribbons is offset slightly by the higher cost of the special paper.

It's only got to brush its heating elements over the surface, as the print head doesn't have to strike the paper to form an image. Also, thermal printers ought to be much quieter than dot matrix ones to make its mark. Not so though, I'm afraid - to bring the price down the manufacturers often use fairly cheap electric motors to feed the paper and scan the print head, so you get a different sort of noise, but it's not quieter. It's no coincidence that the least noisy of the printers I tested was also the most expensive.

If you plump for one of the most basic of the thermal printers, you won't need an interface. They are designed as plugin replacements and work directly from the Spectrum bus. The others have standard RS-232C or Centronics ports, so you need a printer interface as well - take this into account when you're considering your budget. For the extra though, you'll get many of the features of the big machines, including emphasised, condensed and enlarged fonts, variable line spacing, international character sets and bit image graphics.

IN THE PICTURE

Bit image graphics means you have direct control over the heating elements in the print head. So, you can print any pattern of dots onto the paper. Interfaces such as the ZX Lprint contain the software that uses this facility to perform a screen dump, so duplicating the COPY command. Although you'll have to bone up on the graphics modes before you get to grips with them fully (especially since most Epson-compatibles are Japanese, with manuals written in Janglish!), they do allow you to draw dot graphics of any kind, unrestricted by the Spectrum screen size or resolution. And as they all use roll paper, you could write a program that printed a frieze type of picture.

NO LIMIT?

Bear in mind if you're considering thermals that, with one exception, none of them can handle A4 width paper, or even cut sheets. Using roll paper means that the top and bottom of your printouts have ragged edges where you've torn them off. Still, that's OK if you only want the printer for listings - or if you're happy sending out letters that look like supermarket checkout receipts.

You'll also need another spare mains socket. All but one of these printers require an external power supply, of the small transformer PSU type. Two of them can run off batteries, but they eat them and if you don't use re-chargeables, your running costs will be unbelievable.

WHAT PRINTER?

Before choosing one of these printers, you'll have to decide exactly what you're going to do with it. If you're looking for a straight replacement for the ZX Printer, then the Floyd 40 is your best bet. Unlike the Alphacom it does a lot of clever tricks besides duplicating a Sinclair printout.

However, if you're likely to be writing letters and so forth, you'll need to look up-market a bit. There, the Epson P-40 equals the Brother HR-5 on features, but for the extra fifty quid, the HR-5 lets you use cut A4 sheets and offers the back-up of ink ribbon if you run out of thermal paper. Remember though, that you'll need an extra interface for both of them.

ALPHACOM 32

Dean Electronics,
Glendale Park,
Fernbank Road, Ascot, Berks.

When it comes down to performance, the Alphacom 32 is simply a souped-up ZX Printer. It will LPRINT, LLIST and COPY in exactly the same 32-column format and nothing else. It won't recognize any of the standard Epson control characters which alter the print width, font style or anything else. And you won't get the graphics commands in any other form than the COPY mode. It even prints a question mark if you send it a line feed code! For my money, this makes it the least useful of the four printers.

I tested the blue thermal paper (though you can get black) and found it easier to read than a ZX printout, but the print quality was about the same. The printer also kicked up a bit of a racket - there was a constant grinding of the powerful, geared motor throughout the printing cycle.

The machine has a similar footprint to the Spectrum. There's a through connector for other peripherals but the thick connecting cable puts pressure on the power input jack so you can't tell whether it's on or not - it uses non-latching membrane one-off switches and there's no LED indication. The plus is that it's a plug-in-and-go printer, so no software setting-up is required.

HARDWARE WORLD

With ever-increasing amounts of peripherals available for Sinclair computers, users are finding it more and more difficult to know what to buy. We present a buyer's guide to joysticks, keyboard and printers and review the best of the rest from the 1984 add-on market.

The decision to buy a printer to complete your computer system will be one of the most difficult and certainly one of the most expensive which you as a Sinclair user will have to make. The variety of printers available tends to confuse rather than facilitate your choice and many of them are likely to cost more than the rest of your system.

Yet if you are intending to use a Sinclair machine for something other than games playing, you will, sooner or later, need to make a permanent copy on paper. With that in mind Sinclair User looks at 11 printers, from the inexpensive to those suitable for small businesses.

The first consideration must be the purpose for which you intend to use a printer. All the printers reviewed will produce listings of programs, some faster than others and some more legibly. If you intend to do some word processing the type-style and method of printing is also important.

Most of the machines reviewed are dot matrix printers. That means that, just as characters on the screen are composed of a number of dots - pixels - the printer has a number of little pins which are pushed on to the paper, through the ribbon, to form the character. The greater the number of dots the better the definition of the character.

Just as user-defined graphics are made by changing the arrangement of the dots, dot matrix printers can easily change the type-style or the character. The printer holds those definitions in ROM and by telling it which set you want to use it can print in different type-styles and use different national characters, in some cases even Japanese.

Some of the printers use different methods. The Alphacom 32 and the Brother EP44 are thermal printers. That means they use special, more expensive paper although they are still dot matrix types. The pins become hot and cause the paper to change colour. The Brother can also use plain paper with the addition of a special ribbon.

The Dyneer DW16 is a daisywheel printer, using a wheel which has each character, like those on a typewriter, at the end of a spoke. To change type-styles the wheel has to be changed.

The Olivetti JP101 has a small cartridge which fires an ink-jet at the paper. As there are few mechanical parts the printer is quieter than most.

The Tandy CGP-llS has four ballpoint pens which form characters by moving the pen horizontally and the paper up and down.

The speed of a printer normally is measured in characters per second; in theory the higher the number the greater the speed. To test that we used a standard body of text, the first chapter of Genesis, and timed how long it needed to print. The text was prepared using Tasword 2 and printed via a Kempston E Interface, where suitable, a total of 796 words over 77 lines.

The results were surprising. The Microline 80, with a quoted speed of 80 cps, took nearly twice as long as the Mannesmann Tally MT80 and three times as long as the Olivetti. The answer would be to take such quoted figures only as a very rough guide.

Another thing to consider is how you want to drive the printer. Two of the machines reviewed connect directly to a Sinclair computer, the Alphacom 32 and the Seikosha. While that is undoubtedly the cheapest method, when and if you upgrade your computer you are left with a printer you may not be able to connect to your new machine.

There are two standards by which printers normally are driven, Centronics and RS232. Roughly speaking, Centronics interfaces have eight wires so that the bits of each byte travel to the printer at the same time along each wire. Serial interfaces have one wire and the bits travel along it one after the other.

Whether you use Centronics or RS232 does not make much difference so long as you do not try to mix them. On many of the printers Centronics is fitted as standard and RS232 is available as an add-on at extra cost.

Your future plans must be taken into consideration. Users with a Microdrive can use the RS232 port fitted. If you are thinking of buying a QL it also has an RS232 port fitted as standard. Other add-ons such as modems also tend to use RS232 and so the system has advantages, despite the extra cost.

The width of paper the printer can handle may also be a consideration. Normal listings may use only 32 columns but if you like to add REM statements at the side or for word processing, 80 is the minimum.

It is often necessary to indicate to the printer what you want it to do, whether changing the type-style or feeding paper through it. There is a standard for it known as ESCape codes, i.e., codes which escape from normal printing to do something different. Those codes were originated by Epson and are now used by most other makes of printer.

To help you each printer is now considered, briefly, in turn. The Sinclair printer has not been included as it has been discontinued and will be available only while stocks last.

Alphacom 32 is the cheapest on the market at the moment. It has reasonable print quality and is easy to use. It has only a ZX-81 size connector, so Spectrum users must use it as the last add-on. From Dean Electronics or Prism.

Seikosha GP50S is an inexpensive plain-paper printer, not particularly fast and rather noisy but easy to use. It has a Spectrum-size edge connector, so ZX81 users will need an extender card not yet available from Seikosha, so try Eprom Services. From DRG or Prism.

Tandy CGP-115 is the cheapest colour printer; it is very slow but can do pleasant graphics with the appropriate software. From retail shops.

Microline 80 is supplied with roll paper holder as standard. It uses ordinary typewriter ribbons. It has only one type-style. From X-Data.

Brother EP44 is a portable typewriter with RS232 connection. It is not really suitable as a computer printer but as a typewriter it is amazing. From local typewriter shops.

Olivetti JPIOl is a quiet ink-jet printer; it has slightly blurred print but is reasonably fast.

Epson RX80 is the standard by which other printers are measured. It is versatile with clear print and all the facilities you are liable to need.

Star Gemini-10X was caught by a recent price reduction for the Epson, which it mirrors. It may be discounted further. From London Computer Centre or Micro Peripherals.

Mannesmann Tally MT80 is a good-looking printer, also heavily discounted.

Canon PW1080A is very fast and has a good range of facilities, including programmable characters. It is slower in near letter-quality mode. From London Computer Centre or Micro Peripherals.

Dyneer DWl6 is a business users' daisywheel printer. The code is compatible with Diablo printers. From X-Data.

British Olivetti Ltd, 86-88 Upper Richmond Road, London SW15 2UR.

Dean Electronics Ltd, Glendale Park, Fernbank Road, Ascot, Berkshire SL5 8JB.

DRG Business Systems Ltd, Peripheral Division, 29 Lynx Crescent, Winterstoke Road, Weston-super-Mare, Avon BS24 9DN.

London Computer Centre, Grafton Way, London N1.

Mannesmann Tally Ltd, Molly Miller Lane, Wokingham, Berkshire RG11 2QT.

Micro Peripherals Ltd, Basing, Basingstoke, Hampshire RG24 0BY.

Prism Microproducts Ltd, 18-29 Mora Street, City Road, London EC1.

X-Data Ltd, 750-751 Deal Avenue, Slough Trading Estate, Slough, Berkshire SL1 4SH.