EPROM BOOSTS BASIC FACILITIES

Orme Electronics Eprom Read card for the 16K and 48K Spectrum fits into the ROM space which is unused at present and can provide more facilities for Basic programs. With the EPROM I fitted, 10 extra routines are added for program editing, such as block delete of any section of program, renumbering, variables dump. Commands which can be used in programs include left and right scrolls of the screen, TEXT justifier - to the printer only - and a very good sprite routine which will allow you to print various-sized characters at any location on the screen.

It will also allow you to turn round the characters by 90 degrees and print them in inverse and/or over other characters. There is also an extra graphics set which can be called-up from the ROM into the user-definable graphics area.

Each of the routines is used by giving a RANDOMISE USR-variable-command. An OUT command must also be used to change to a different section of routines as only 1K of the ROM is available at a time. The first routine is called by a number every time the program is RUN and that sets up the variable names to be used in the rest of the program. So, for instance, RANDOMISE USR REN would renumber all the lines in increments of 10 from 10.

The routines are easy to use if the examples are followed to the letter. VRD-variable dump-works only on variables created after the variable set-up routine and deletion of lines works only with lower-case REM del statements.

PRICES UPDATE

The EPROM board for use with motherboards costs £18.50 and the direct connecting type £21.25. Tape control costs £3.45 extra, as does EPROM I at £9.95. Postage and packing costs 75 pence for the U.K. and £1.75 overseas. Orme Electronics, 2 Barripper Road, Camborne, Cornwall TR14 7QN. Tel: 0209-715034.

THE INGENUITY OF THE PERIPHERALS MANUFACTURERS HAS CONTINUED AND SINCLAIR RESEARCH FINALLY LAUNCHED THE MICRODRIVE. STEPHEN ADAMS REVIEWS ANOTHER INTERESTING YEAR FOR SINCLAIR USERS.

INGENUITY BEATS SPECTRUM LIMITS

Stephen Adams summarises the add-ons.

The biggest blow to users of non-Sinclair-produced equipment was the announcement of the Spectrum. It knocked most memory-mapped add-ons on the head, as no provision for those devices had been made. That was because, unlike the ZX-81, there was no way of turning-off the internal RAM from the expansion port. The only thing left was for producers to put things in the input/output map or to supply RAM packs or RAM upgrade kits.

The I/O map was already full of Sinclair devices, allowing the use of only eight separate devices, if they wanted them to be compatible with the Microdrive. Nevertheless, ingenuity brought forward a large number of new devices after the initial shock had worn off.

RAM kits for upgrading the 16K Spectrum to 32K are now readily available for about £21. Fox Electronics, for example, supplies a kit for £20.99 and it has instructions on how to improve your TV display. They are easy to fit and now have simple instructions on what to do, if you can overcome the fear of opening the case. The kits are usually identical to the proposed Sinclair upgrade but will fit only on model 2-type Spectrums. East London Robotics can also supply an extra 64K kit which is paged.

For those with a model 1 Spectrum, identified easily by the grey keys, there is the choice of an add-on board made by Downsway Electronics or the Spectrum 32K RAM pack by Cheetah Marketing. The Spectrum RAM pack will also fit on to any other Spectrum, as it plugs into the expansion port.

Another memory-mapped device available this year was in a surprising place, inside the Spectrum 16K ROM space. It was the Orme Electronics ROM containing RENUMBER, block delete of Basic lines and many other usefiil routines in a 2K ROM. That can be very useful, as it is immediately available on power-up.

Sinclair has also provided new devices in the ROM space, which should please hardware and software users. One is the Microdrive Interface One which not only contains the controlling ULA and hardware to run the RS232/network/highspeed cassette Microdrive but an extra ROM which can be used to write your own Basic commands. The other is the ROM cartridge system available with Interface Two.

The RS232 can handle a printer easily with its limited handshaking ability but Still is limited for input from an RS232 device, as all that is under software control and not a hardware chip. The network is a very simple arrangement which allows you to talk between 64 Spectrums but I have no doubt that someone will write similar software to use it with the ZX-81 through the cassette sockets. Two books which should help in this respect are those by Andrew Pennel and Dr Ian Logan.

The Pennel one also contains an ON ERROR GOTO machine code routine which should trap 90 percent of Basic errors and send them to a program line to deal with them.

Sinclair has also launched the Interface Two, containing two joystick sockets which will operate the first or last set of five number keys. That will mean that software will have to be re-written to use Sinclair joysticks, as the accepted standard at the moment is the one set earlier in the year by the Kempston joystick interface which operates as an I/O device, depending for its decoding on A6 only being low.

Much software has already been converted to use it and I cannot see software writers wanting to do it all again. Programmable joysticks are just starting to reach the market, which will eliminate the need to rewrite the software.

For the Spectrum and soon the ZX-81, the Stonechip one seems to be best. For ZX-81 and Spectrum users, a cheaper hardware-based version, the Pickard controller, can be used as it fits both computers by plugging into the keyboard sockets. The AGF version uses crocodile clips to set up the five keys to be used; it is a little unstable but it plugs into the edge connector and does not require entering the machine.

The Interface Two also has a single ROM socket which allows you to use Sinclair-designed cartridges. It is not known whether software suppliers will want to try to fit normal ROMs to a port like this. That, and the fact that recording Microdrive cartridges is a slow process, will limit the amount of software available from software manufacturers on Sinclair devices. EPROM software for ZX-81s is available from Eprom Services and Audio Computers.

Both, however, concentrate on the machine code user and not the games player. The fall in price of the ZX-81 and the amount of hardware available for it has started to attract the business user as a control processor for a robot or controlling some industrial process.

That is because it contains all the requirements of the development system on one board - Z-80-A, one of the most popular processors, working at 3.25MHz, TV interface, cassette interface for program storage, alphanumeric keyboard, Basic as well as machine code monitor for designing programs, and an expandable memory map and I/O map.

There is also a wide range of machine code assemblers, disassemblers, EPROM cards and blowers, RAM, battery-backed memory already available, costing just a few pounds. That to the industrial process manufacturer is peanuts, as a development kit from a chip manufacturer would cost more than £200 with far fewer facilities. The ZX-81 costs only £45 with a massive 16K memory included.

Plain-paper printer interfaces for the Spectrum abound and Tasword, the word processing program, can work with most of them. Hilderbay and Kempston provide software-driven Centronics versions, while Morex provides both RS232 and Centronics outputs. Deans also introduced its version of the Timex printer, which uses a much better paper than the Sinclair, gives a clearer print in both black and blue ink, and will use Sinclair commands to control it, so there is no need for extra software.

Printers and other hardware devices make the software "come alive" and that combination makes the Spectrum a very powerful business computer.

That is the most important event of the year, as the more software which is written to use the large amount of hardware, the more that hardware will be used. Voice output units, modems - to talk to other users or databases over the telephone - RS232 interfaces and light pens all rely on good software to make use of them.

The Cheetah Marketing Sweet Talker, for instance, works better because it is accompanied by an instruction tape which not only demonstrates how to use the unit but also shows the user how to structure programs to make it easier to use in their programs.

Modems from Maplin, Ambit and Micronet - for Prestel - will allow users of the Spectrum and, in the first two cases, the ZX-81, to talk to many other computers. Some of them will be other types of computers, like the BBC and the Commodore 64. The others will be maintained by public and private companies which maintain large amounts of information and programs on their computers.

Micronet 800 is a database maintained on Prestel computers as a 24-hour-a-day, seven-day-a-week computer club. It has hints and tips on Spectrums - ZX-81s at the moment cannot use the system - as well as news, free programs and a mail box facility. Keyboards and consoles also have been making their presence felt as ZX-81 and Spectrum users want to upgrade their machines. Plastic cases from W H Smith are about the cheapest containers at £3.99 and will take a ZX-81 or Spectrum, as well as a few add-ons. The d'Ktronics keyboard and case or that from Fullers appear to be the most popular but neither will allow the use of the Microdrive interface without taking it out of its case.

The Filesixty button set is a cheap alternative for ZX-81 users which gives the advantage of spring-loaded keyboard the same size as that of Sinclair, but without costing more than £10.

Colour for the ZX~81 is now available in a simple form for all PAL television users - that is, most of Europe. The black box requires only two wires to insert between the modulator and the breaking of tracks and can be re-connected if required. The rest of the box plugs into the back of the ZX-81 to give black characters on a choice of 16 coloured backgrounds or coloured characters on a black background from DDC. It is also more stable than the Spectrum and requires no extra memory to use it. It will work even on a 1K machine.

One device which requires extra memory is the excellent High-res screen - 192 by 256 pixels - and user-definable graphics package made by Nottingdale Technology Centre. It uses the ZX-81 internal 1K RAM for its system variables and 6K of memory for the storage of the screen in the program. No internal wiring is required, as the unit plugs directly on to the back of the ZX-81.

For the Spectrum, a unit has appeared which will be of great delight to children and disabled users. It is the Currah microSpeech unit which plugs into the back of the Spectrum and, on command, will speak the key pressed. That happens during program input as well as INPUT and INKEY$.

It requires no programming of the speech by the user. Speech output can also be programmed by using S$ to contain the allophones - sounds which make up words - which are then spoken immediately. Thus input and output can be spoken rather than read.

Tapes have been causing problems ever since the ZX computers came into existence; the Spectrum is better than the ZX-81 but still can be improved with some extra hardware.

Tape filters and switch-controlled SAVE and LOAD devices are available from several firms, like Abacus and Elinca. There have now been three Spectrums produced by Sinclair. The model is, which can be identified by the grey keys or by looking through the expansion interface and seeing an IC socket on the left-hand side; the model 25 have the large, black, ROM chip there. Those Spectrums need their extra 32K of RAM mounted on a printed circuit board before they can be put into the computer. There are no Sinclair RAM boards available for the machine.

The model 25 were re-designed completely by a computer and the ULA was changed to get rid of an extra 1C which had to be inserted in the model is, due to a design error. The extra 32K of RAM which can be added to 16K machine now requires only chips to be plugged into sockets on the board. Model 1s and model 2s have had to have an extra transistor fitted to prevent a clash between the keyboard and the ULA TV interface.

The latest model 3s have also had their internal circuitry re-arranged and the ULA updated to give a wider tuning range on TV sets. It has also caused some software problems, as the keyboard inputs are no longer held to binary l - + 5 volts - when not in use. That was done to reduce the power 1 requirements of the ULA.