ZX Computing

Interface 2

Author: Peter Shaw
Publisher: Sinclair Research
Machine: Spectrum 48K/128K/+2/+3

Published in ZX Computing #11

Our reviewer, Peter Shaw, takes a look at one of the latest Sinclair releases

Interface 2

Sinclair's new black box appeared where we were still trying to get over the Microdrive launch. ROM software is something Sinclair users will not have come in contact with unless they have a video game machine, and even then there are many differences.

The Facts

Before I go on, I'll explain exactly what the Interface 2 is: A two-joystick interface plus ROM cartridge software socket, contained within a small black box, oddly shaped with a stepped level which is difficult to describe without you actually seeing one.

The ROM cartridge idea was pretty smart, although the software that is available at the moment is obviously biased towards the game player. I would have preferred to see a word-processor, like Tasword, or a disassembler, like Zeus, on cartridge. These sorts of programs are more suited towards the ROM slot. Obviously, you cannot 'save' your own programs on cartridge, and with commercial cartridges at £14.95, I doubt whether anybody will have more than three cartridges in their collection.

The physical shape of the cartridges, and the way they are connected to the slot is very odd. The cartridge has a red plastic 'skirt' which rides up to reveal an edge connector: on the Interface itself there is a female connector below a plastic 'door'. In theory, the cartridge simply plugs in the female connector, just by pressing the cartridge in. It took me some time to get one of the cartridges in the right place. I don't think it's going to do the Interface a lot of good with all these users shoving their cartridges in willy-nilly.

The joystick interface will accept any 9-way D-type connector joystick, i.e. the Atari or Kempston sticks. The joystick connectors are protected by two small covers which took me all of two days to lose. Joysticks can be plugged into, and unplugged from the computer at any time without causing it to crash.

Joysticks 1 and 2 work on the keys 1-0 in the following way; the instructions supplied with the Interface was not without many errors, carefully corrected with a black biro.

Key Joystick 1   Key Joystick 2
1 Left   6 Left
2 Right   7 Right
3 Down   8 Down
4 Up   9 Up
5 Fire   0 Fire
Of course, in Basic you could not read more than one key at a time using the INKEY$ command. But you can use the IN command;
IN 63486 Joystick 1   IN 61438 Joystick 2
bit 4 Fire   bit 0 Fire
bit 3 Up   bit 1 Up
bit 2 Down   bit 2 Down
bit 1 Right   bit 3 Right
bit 0 Left   bit 4 Left

A Conclusion

The Interface is pretty good value at only £19.95, but the cartridges are very pricey at £14.95. It might be worth buying the Interface just for the joystick interface, which are obviously become standard. Sinclair Research, 25 Willis Road, Cambridge CB1 2AQ.

Peter Shaw