THE ZX PANDA is a 16K expandable RAM pack from Stonechip Electronics. The black plastic case is designed to wrap neatly round the back of the ZX-81 and thus not to wobble. The edge connector is also different in that it is tin-plated like the edge connector on the ZX-81 to stop dirt build-up due to dissimilar metals.
Most RAM packs use a high-quality gold connector and that can cause a battery-type effect on the contacts, which causes oxide to be formed on the edge connector.
The RAM pack worked first time under test and exhaustive thumping of the keyboard - far in excess of normal use - could not budge it. A red miniature LED on the top of the case also indicates that power is reaching the RAM pack. There is no extension PCB at the back but an expansion board containing another 16K can be added inside the plastic case. That brings the total RAM to 32K.
To attach the extra RAM the case can be pulled apart - there are no screws - and the expansion board plugged in. Care must be taken plugging-in the board as the sockets used are strip ones which have to be lined-up underneath the pins. The board is designed, however, so that it can go only in the correct way. The ZX Panda can be obtained from Stonechip Electronics, Hampshire. The cost is £19.95 and the 16K expansion module is £14.50. Both are available from Fox Electronics and other shops as well as Stonechip.
KEYBOARD BUTTONS is an idea from Ian Samways and consists of clear acrylic discs 3/8in. in diameter which stick to your ZX-80 or ZX-81 keyboard. The buttons allow you to "feel" where the centre of the key is while looking at the TV.
They have a piece of paper stuck to the back which, when you have cleaned the keyboard with methylated spirit or something to remove the grease, can be removed and stuck in the centre of the key. Being clear, it does not obscure the markings on the keyboard.
Easy to use and simple to apply, this should be popular for most ZX users at a price of £1.95 for a packet of 40. Schools which use ZX-81s could benefit with a few spares as they are sure to be easier to use.
AUDIO COMPUTERS can supply the same anti-wobble device as fitted to its 16K RAM packs. It consists of a plastic shape which is fitted over the edge connector. When the RAM pack is inserted into the back of the ZX-81, two tongues are forced between the edge connector and the case. Two other plastic feet slip underneath the RAM pack.
The cost of the anti-wobble device is 50 pence and at first it looks good value but tried on the 16K Sinclair and other RAM packs it has been discovered that using the keyboard vigorously makes the RAM pack 'wiggle' its way out of the expansion port and fall off. That is disadvantageous both to computer and RAM Pack.
On its own RAM packs it also has two double-sided sticky pads stuck above the edge connector to hold the RAM pack on to the ZX-81. Tried with the ZX-81 without the anti-wobbler, the problem was solved, so be advised that a pack of sticky fixers will work wonders; they cost about the same as the device but they fix 20 ZX-81s.
THE PLUG-IN mains plug with a difference contains an interference filter as well. The plug is in white plastic and is about 4½in. high and 2in. wide. The fuse in the plug is rated at 3.15 amps and is of the small glass type usually found in radios and TVs, about 1in. long. That should not be replaced with a fuse of a high rating as it would damage the filter inside the plug.
The filter is made up of a ferrite ring wound with two coils, one in the live lead, the other in the neutral. Earth connection is provided but not usually used on Sinclair and other computer game power supplies. The filter is encased in a plastic block and has an additional transient suppressor capacitor to stop high voltages reaching the power pack.
The connection to the computer is via a screw-down terminal block at the bottom of the plug and should be easier to use than a normal plug.
The plug will protect a computer against high voltages due to motors and other equipment being switched on near them. It will also filter out any radio interference generated by refrigerators and TVs coming through the mains. It should be ideal for those experiencing unexplained white-outs due to mains interference but not voltage drops and can easily be transferred to another computer when you upgrade at a later date.
The plug is available from Power International Ltd, Portsmouth at £15.50 inclusive. Also offered is an advice service for users still having problems.
TRAFFIC TECHNOLOGY has updated its desk Console range to include the Spectrum. To keep a desk tidy it is ideal as it will take a tape recorder, two cassettes, printer, power pack, Spectrum and Microdrive RS232 for which we are all waiting.
The console also has a switch panel on the front to allow you to change the cassette leads from LOAD to SAVE, plus an on/off switch for the 9V power supply to act as a re-set switch. The case is made from tough ABS plastic and is 555mm. wide by 370mm. deep and 50mm. high. The bottom of the case is held together by four screws for easy maintenance.
Optional extras are stacking pillars for more than one unit, and dust covers. The cost of the Console is £42.18 including post and VAT in the U.K. People outside the U.K. should allow for a package of 1.5kg. Traffic Technology Ltd, Wiltshire.
SOFTEST has produced an interface to allow you to use the Tandy four-colour printer plotter. Although the Tandy has RS232 and Centronics, inputs, an interface box and software are required to use the printer. Softest provides them in a package costing £35.
The printer can be used to LIST programs from the Spectrum using a machine code routine and the three-part program also allows you to draw graphs and print characters in a 40- or 80-column width. Plain paper is used 4in. wide and the four colour ballpoints in the unit are black, red, blue and green. The paper can also be moved up and down under software control. For more details contact Softest, Hampshire.