| hardware world |
| From black boxes to boards ... to-the-point assessments of hardware now on the market |
A PIECE of hardware not intended to fit on to the ZX-81, Print 'N' Plot Jotter is a pad of paper which consists of two grids, one for plotting Pixel graphics and one for printing Alphanumeric characters. They are intended for the programmer who wants to improve his programs and save time by planning his displays on the screen before PRINT AT X: Y: ALPHANUMERIC or PLOT X; Y a pixel.
The Print 'N' Plot Jotter is also useful to use with the Sinclair printer, as was shown at the ZX Microfair, by the firm producing an aeroplane plotted on paper more than one foot long. A polyester film version is also available for transferring book or magazine pictures to the ZX-81.
The Print 'N' Plotter Jotter costs £3.50 for 100 sheets and the film £2.25. Both are available from Butler Currie and Hook, London.
HAVEN HARDWARE has gone one step further than producing a real keyboard and produced a circuit which will make any key on the keyboard repeat after one second. It will allow you to cursor right a number of times, back to a mistake made in a INPUT line, by holding down two keys. It is available on the printed circuit board for the Haven keyboard or can be attached to another keyboard by soldering it to the ZX-80 or ZX-81.
The keyboard module costs £2.50 as a kit for another keyboard or £2.50 for the components to mount on to the Haven keyboard.
Haven Hardware is at Workington, Cumbria.
High-res graphics |
QUICKSILVA has produced a high-resolution graphics board which will produce BBC-type plotting of lines, boxes and other dot graphics. The ZX-80 and ZX-81 'chunky graphics' with a maximum resolution of 43 x 64 pixels is replaced by a screen offering a resolution of 192 x 256.
Each dot on the screen can be addressed by an X/Y co-ordinate in a REM statement, which may have more than one command in it. All the USR routines are stored in a 2K ROM mounted on the board, so no machine code REMs are required.
Drawing lines, boxes, or only dots can be done in either black or white, while clearing the screen requires writing-over the dots with the background colour. Alphanumeric characters can be used and there are commands to clear the screen in black or white.
The board costs £85 inclusive and Quicksilva is at Maybush, Southampton.
CALLED a FIZ - Floppydisc Interface for the ZX81 - the Macronics floppy disc provides a standard 5¼in. floppy disc drive, software in a 2K ROM and a motherboard in the same unit.
The disc will provide 43K of storage which can be LOADed at a rate of 8K in 22 seconds. The disc has 34 tracks and 10-128 byte records on each track, for storing data or programs. The commands are given to routines stored in ROM, so that no RAM is wasted and all the disc commands are written to be used from Sinclair Basic.
The motherboard provides all the power for the system, including ZX-81, and interface cards to a paper printer will be available soon. There is also the possibility of a networking card soon.
FIZ costs £303.03 inclusive and is available from Macronics, Solihull, West Midlands.
IF YOU run out of paper, what do you do? Do you panic and send next time for twice as much as you need from Sinclair? Now there is an alternative supply which should be quicker and cheaper than Sinclair.
Silicon Tricks can supply five rolls of electrostatic paper, the same size as Sinclair paper, of similar quality. The price for the five rolls is £7.50, whereas the Sinclair cost is £11.95. Ten rolls cost even less per roll, at £14.50. They are available by mail order only. Silicon Tricks, London.
A RAM extension kit is expandable in the form of 2K blocks up to a maximum of 16K, as and when you need it. It requires no soldering connections and fits in the ZX-81 beneath the keyboard.
If you later decide to buy an external 16K pack, the internal RAM can be altered to fit into the next 16K section, so that you can have continuous Basic memory up to a total of 32K.
There are two kits available, 2-8K RAM costing £8.50 and 2-16K at £9.50. Details are available from East London Robotics (Electronics), East Ham, London.
FORTH, the language in which you can build a vocabulary of your own commands, can now replace Basic on your ZX-81. This version of Forth resides in EPROM like the Sinclair Basic and is therefore available when switching-on the power, with no LOADing problems.
Forth programmers write the commands in the form of subroutines, which are then COMPILED into machine code, so that they run faster than their Basic equivalent.
Forth is available from Artic Computing, Hull, North Humberside.
High quality joysticks |
THERE ARE now proper joysticks with a smooth action and fire button, like the expensive computer games machines, available for the ZX-81. The joystick is attached to the ZX-81 via a controller board which plugs into the back of the ZX-81 and has a connector on the back for the 16K RAM pack printer.
The joysticks are used by selecting the movement to be tested UP/DOWN, LEFT/RIGHT and then using the PEEK command to see the position of the joystick. That can give a result between 27 and 114 but it can be altered on the board.
All the instructions can be in Basic or machine code and the cost of the joysticks is £9.60 each, with the controller board costing £129.80. Space Invaders and a Maze game are already available from Micro-Gen, Bracknell, Berkshire.
BLANK printed circuit boards are now available for experimenting with the expansion bus or motherboard of ZX machines. They have a gold-plated edge connector on them, in which only a slot for the keyway needs to be cut. As they are coated on both sides in copper, you can design your own circuit to use the ZX-81 as a controller of devices and then etch away the copper at home.
That leads the way to even more products for the ZX machines, as the cost of making experimental boards falls.
Cambion Electronics produces the board for £3 and can be reached at Castleton, Sheffield.
THE LATEST device from RD Laboratories for its 8100 system is a light pen which, when used with the slow mode of the ZX-81, can impact with the program on the screen. That means that drawing pictures on the screen, using alphanumeric characters, or plotting using pixels is as easy as drawing them on a piece of paper.
It can also be used to select from a menu of items, as in a multiple-choice question, without making a mistake by pushing the wrong button. All that can take place using Basic or machine code.
The light pen system consists of a Micro-Mum (RD8100) motherboard, light pen and access unit (RD8180), plus a free demonstration tape of software. The cost is £49.50 from RD Laboratories, Ware, Herts. It is one of the many modules available for the system.
REDDITCH Electronics will supply everything from a ZX-80/81 edge connector to a programmable timer-counter oscillator on one board. It can also supply motherboards, keyboards, A/D and D/A converters and power supplies, as well as books. The boards are available in kit or ready-built form.
The firm knows Sinclair Research equipment well, as it was one of the few which supported the first Sinclair effort in computing, the MK-14, long after Sinclair had abandoned it.
Redditch Electronics is at Redditch, Worcs.
A BLACK BOX which plugs into the edge connector of the ZX-80 or ZX-81 giving 5K of Basic memory and an input/output sort is known as the 'P' pack, the basis of the DCP system. It is accessible from Basic via the PEEK and POKE commands, and the port is memory-mapped.
The input/output section can be attached to two other modules, one at a time, to give A/D-D/A conversion or larger current-handling capacity via replays. The D/A pack is known as the 'A' pack and the relay as the 'C' pack. The price of the 'P' pack is £37.95, 'A' pack costs £19.95 and 'C' pack £29.95. They are all enclosed in tough black boxes and, like the 'P' pack, contain instructions for use with other circuits. A speech talker will soon be available.
DCP is at Norwich, Norfolk.