| hardware world |
Kempston's new keyboard. |
KEMPSTON Electronics has produced a micro-miniature version of the ZX-81 keyboard with real keys. It is the same size as the original Sinclair keyboard and so can be placed on the top of it. It is only half-an-inch high and its black keys blend well with the ZX-81.
The keyboard can be fitted by opening the case and removing the original leads to the sockets on the PCB and replacing it with the leads from the Kempston unit.
The company also produces an Educase which exposes the printed circuit board to the naked eye, for students and teachers to see through the clear plastic cover.
It is ideal for demonstrating the working of a computer; the back can contain a parallel port complete with a demonstration program to run a Centronics printer. Unfortunately there are no Sinclair graphics. The keyboard costs £22.50, Educase £19.95, and the parallel port £18.95.
DCP has produced a speech pack which can be fitted directly to the back of a ZX-81 and which will not interfere with any planned expansion. Using a maximum of two memory-mapped ports at 49148 and 49149, the various ROMs containing the words can be POKEd via Basic to the loudspeaker included inside the unit.
The speech can be heard through the loudspeaker or, if required, can be amplified via the jack socket provided - 8 ohms. The amount of words it can say depends on the number of ROMS fitted inside the box. A maximum of four can be fitted and the basic model is supplied with the first one.
Most of the words are measurements of one kind or another, but PAUSE statements between words can be altered so that you can create your own from the words supplied. You are limited to the beginning of words, however, as the speech is stored only in complete words, not sounds.
The speech pack costs £49.95, complete with ROM 1, and extra ROMs are available at £14.95 each, including VAT and postage.
THURNELL ELECTRONICS has now extended its range of equipment for the ZX-81 to include a motherboard, LED indicator board, transistor driver board, relay board to control up to 1.5A AC or 24V DC at 3A. All are in cases but the original I/O port is still available in kit form and without a case.
A motherboard can connect up to four devices to the port at once. The port is based on a Z-80A PIO and so is completely compatible with the ZX-81. It costs £14.95 as a kit without a case and £ 17.95 fully-assembled with case. The eight-transistor driver box costs £9.95, and motherboard £15.95. For orders of less than £20, add 50 pence for post.
CAPITAL COMPUTERS has produced the first motherboard with bank-switching incorporated on-board. The expansion motherboard also sorts out the reflections of the ROM and RAM so that the full 56K left can be used. It includes a +5V regulator for a separate power supply, an optional metal case, and a range of plug-in boards.
The boards contain 16K of extra memory, full RS232 serial interface to drive printers, Centronics parallel interface for printers complete with handshaking, and a 2716 ROM containing the driver routines.
All the expansion motherboard sockets are buffered so that the pulling-out of cards should not crash the system. The expansion motherboard costs £40.20, serial/parallel interface board £45.95, 16K RAM £33.93, and the metal chassis £19.50.
All are obtainable from Capital Computers Ltd, St. Albans.
FULLER Micro Systems has added a new board to its range of equipment which can fit inside its keyboard case. It starts as an ordinary 16K board supplied with the industrial standard 4116 chips but if you decide later that you need more memory you can upgrade the board to a full 64K by changing the RAM chips and a few straps on the same board.
The 16K PCB will fit into any motherboard which provides sockets for boards to plug into and costs £39.95. To upgrade it to full 64K will cost another £45 for instructions and the 64K chips to fit to the board.
The complete Fuller Micro Systems range can be seen and purchased from The ZX Computing Centre, Liverpool.
TV SERVICES of Cambridge has a neat little keyboard bleeper called the KAT keyboard audio tone. The device can be fitted inside the case in the space beneath the keyboard, or in any other place for that matter, as it is an extremely flat PCB and piezo-electric loudspeaker.
There are only five soldering connections to make to the ZX-81 PCB, as the rest is ready-assembled. If that makes you nervous, the company will fit it to your ZX-81.
The bleeper gives two tones, one when a key is pressed and one when the computer answers; it also signals the start and finish of a LOADing or SAVEing program. It may also be programmed to bleep in a program - for simulating an explosion - by using a PAUSE greater than 5.
The KAT costs £8.95 if you fit it yourself and £10.95 if you send your ZX-81 for it to be fitted.
The 16K RAM pack from Taurus Computer Design. |
TAURUS Computer Design has a 16K RAM pack which also contains a 2K monitor EPROM for writing machine code programs on the ZX-81. It replaces the top 2K of RAM when the switch is thrown on the front of the RAM pack and you can enter the machine code monitor by a simple USR command.
The monitor provides facilities such as hex arithmetic, break points, copying data from one place to another, decimal to hex conversion, fill, memory display, port read and write, plus many more. The monitor will write a suitable-length REM statement at the beginning of a program, so that your machine code routine can be stored there and will even re-set the Basic variables so that a RETURN from the monitor will not crash the program. All is contained in a metal box 6½ x 2½ x 1½in. which attaches to the ZX-81 edge connector via a ribbon cable to prevent crashing the program, due to the movement of the ZX-81.
The 16K RAM pack costs £59.95 with the monitor and £49.95 without, from Taurus Computer Design, Herts.
BASICare has produced the Organic micro, a system which makes incompatibility between systems out-of-date. The idea is that every computer should use the same connections to the RAM packs and ports but, because each time a computer manufacturer produces a new machine it changes the way it connects, that has not been possible previously.
Now BASICare will provide a personality module to convert the ZX-81, BBC computer or Apple in one standard connection, so that any computer can grow from 16K RAM to more than 1MB of RAM.
The packs which use the bus will then be available to be used by any machine to provide printers, ports, Toolkit programs, CMOS and dynamic modules.
The silver packs are connected mechanically as well as electrically, to each other, so there should be no chance of a faulty connection. The basic Persona module costs £30.42 inc. VAT and postage.
METRIMPEX of Hungary is introducing a revolutionary new disc drive system to this country and at least one manufacturer, Macronics, has opted for it. The disc drive is very similar to an eight-track tape recorder, as the disc is stored in a hard plastic box which is opened only when the disc is inserted into the drive.
It can fit in the palm of your hand and can provide up to 200KB of memory on one disc. The power supply is +12V and +5V and it weighs only 9.47 kilogrammes.
The drive provides a standard interface so that it can be used with disc controllers already available. The price in quantity is £50 and details can be obtained from BATS-NCI Ltd, London.