cambridge z88:

Cambridge Z88 (sometimes called Sinclair Z88)

quick facts

Overview Photograph Z88
FCC ID UK-market units do not show an FCC ID. US-market units show GUA3SP Z88.
Model or Part # Z88
My unit's vintage Serial #053151 (UK edition, Enter key twitchy, 128K RAM card), bought from Wolverhampton, UK
Serial #C013260 (US edition, 512K RAM card, 32K EPROM card), bought from Decatur, IL
Serial #C014593 (US edition, Enter key twitchy), bought from Mentor, OH
Unknown unit en route from Rotterdam, The Netherlands
Unknown unit en route from London, UK
Note that the "C" prefix is handwritten on the serial number label with a black biro.
CPU Zilog Z80A
Memory 32K of internal RAM, plus three cartridge slots for up to 3Mb of additional RAM. The RAM socket internally has a 32Kx8 chip in it; this is easily upgraded to 128K of internal RAM. Practically all the Z88s you'll find on the market have a 128K cartridge in slot 1.
Operating System Proprietary multitasking operating system called OZ.
Ports 9-pin (female) RS232, DC input jack, and three cartridge slots. Slot #3 can burn EPROMs or flash ICs; slots 1 and 2 only work with RAM (or EPROM for read only). There is also an expansion port on the motherboard (an edge connector) but the space for this is blocked off in the case. You can see an area of different texture on that part of the case, though, so it was clearly blocked off with a mold insert.
Video/audio output Internal 640x64 pixel 2-level grayscale LCD, capable of displaying >80 columns x 8 lines of text. There is also a speaker.
Available peripherals AC adapter; 128K, 256K, 512K and 1Mb RAM cards, EPROM cards, special modified TRS-80 Model 100/102 disk drives, and more.

The Cambridge Z88 is the last (or perhaps I should say, the most recent) computer designed by Sir Clive Sinclair. It is often incorrectly referred to as the Sinclair Z88, but this is inaccurate; by the time Sir Clive released the Z88, he had already sold the Sinclair name to Amstrad. I acquired three Z88s to date from eBay as part of a small technical research project I'm doing.

Now, just what the hell is it about Sir Clive and rubber? The ZX80, ZX81, ZX Spectrum, and now the Z88 - all with the rubber keys. Even the QL felt rubbery, despite having a semi-real keyboard. Having said that, the keyboard does work rather well, and it's somewhat spillproof. Even though my unit is probably around 18 years old (certainly at least 15), it still works almost perfectly. The design is rather unusual, for a computer anyway. The rubber membrane material is impregnated with carbon on the underside, and there is a grid of fingers underneath it. When you press a key, its underside shorts the fingers below it. I'd give the tactile feel about six out of ten; it's good enough to touch-type, but you can't rest your fingers on the keys because it will cause false presses. The reason I say my keyboard works "almost" perfectly is because the Enter key tends to sag in the center after years of pressing, and now it only takes a very light touch to trigger that key. It has essentially no travel at all.

Apart from this gripe, I think the keyboard is pretty good within its limitations. This is at least partly because the device's software is very responsive and doesn't often miss quick keytaps. I wrote a quick 4,000-word article on my Wolverhampton Z88 this weekend (you'll see it on IBM's developerWorks site in the near future; it's my first Mac mini article) just to test it out, and I think I'm hooked on this machine. I also believe it will be the ideal note-taker in class, since the keyboard is close to being silent.

The Z88 runs off four "AA" cells, with an internal supercap to provide RTC and RAM backup when the batteries die. The main battery life appears to be in the neighborhood of 6 hours of more or less constant typing.

Pipedream, the internal WP software (it also functions as a spreadsheet), is idiosyncratic and not exactly easy to drive, but it is extremely powerful; quite amazing for an 8-bit operating system. You even get a graphical preview of the page you're editing on the right-hand side of the LCD (and you still get 80 columns of text). The diary, terminal, calculator and other software are also very functional, and the inbuilt BASIC is good old BBC BASIC. Lovely. There's also a wealth of third-party software available for the machine.

Take a browse through the photos below (clicking any photo, including the one up top, will take you to a larger version in a new window) and you'll see more of the Z88.

Some more photos will be coming soon, to show you the PCB and also to illustrate the crazy aluminium shielding sprayed inside the US-market Z88s.


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