New 28 October 2004

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BENCHTEST PREVIEW

Cambridge

Computer Z88

Just when you thought he'd become part of computing folklore,
Sir Clive Sinclair reappears with a £200 lightweight lapheld which
sports integrated software and Dozy concurrency. Could this be
Sinclair's finest hour, or is it just another example of theory greatly
exceeding practice? Guy Kewney previews the Z88.

Photography by Tony Hutchings

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If Sir Clive Sinclair's new computer works the way he plans it to work, then he's back in business. Once again, he's doing it on his own. Starting this month, Sinclair's new company, Cambridge Computer, will run mail-order adverts offering the Z88, a lapheld product to be avail- able in May. Sinclair expects a wait- ing list, despite the delay.   The price of £200 and the weight of two pounds make this 'super- portable' 8-bit business system a breakthrough in lapheld computing. The closest on both points is the Tandy 102, which is twice the weight and priced at £299.   Sinclair's machine has far more versatile software, with an integrated spreadsheet, editor, diary and calcu- lator which make it a widely useful design. It also includes BBC Basic. And it has vastly more memory capacity. With a theoretical max- imum size of 4Mbytes of memory, it's expandable - in one way at least - as far as people are likely to ex- pect during its lifetime.   That is, at least, the theory. In order to prepare this report for re- lease at the same time as the machine was due to be launched, at the Which Computer? Show (17-20 February, NEC), we had to take a lot of the detail on trust from the de- velopment team.   What I actually saw of the machine itself was a wood model. The soft- ware was working and (very largely) debugged, but it was running on a Z80 second processor attached to a BBC Master. Some segments of it were running on separate machines, not integrated (there wasn't room) and the memory expansion system obviously requires the kind of elec- tronics that the BBC second proces- sor doesn't include.   For these reasons, although every attempt has been made to put the machine through its paces in accord- ance with standard PCW Benchtest requirements, there wasn't the slight- est point in running any Benchmark programs. The hardware of the final lapheld will run at vastly different speeds, and the designers reckoned that any estimate of overall perform- ance - based on the BBC second processor - would be out by a fac- tor of five or more.   Nonetheless, interest in Sinclair in the UK - and the world - is such that it was obviously necessary to satisfy curiosity by producing an analysis of the machine, designed to coincide with its launch. For that reason, I present here a preview, rather than a Benchtest, with the objective of updating it with perform- ance figures and a full review as soon as a finished machine can be obtained. Technical overview The standard lapheld machine has a

Z80 central processor chip, with 128k of permanent programs and operat- ing software In ROM, plus 32k of RAM. Inside, there are four major custom VLSI chips handling all logic connections and I/O interfaces, plus a small loudspeaker.   Display is an 8-line by 100 charac- ters wide liquid crystal unit from Epson. The keyboard is full type- writer style, slightly reduced in size to fit on the Z88's A4 shape.   Around the edge are sockets for serial I/O, memory expansion and system expansion. And underneath, there's a slot for batteries. Background This machine is not just a flash in the pan, an opportunistic attempt to sell another bit of electronic wizardry. This is the culmination of a dream. Sir Clive Sinclair has been trying to design the ultimate lapheld portable for years and years, starting before he left the National Enterprise Board which was running Sinclair Radionics.   Students of history will know that the original Sinclair Research design, the ZX80, was derived from the New- Brain computer which the National Enterprise Board gave to Newbury to turn into reality. That was intended to be a portable battery-powered system. So was the ZX80. So too, when it was first conceived, was the QL. Indeed, according to some histo- rians, the Sinclair flat-screen TV was originally designed to be a low-cost display for a portable computer. The flat screen was not usable in a port- able computer. It was simply too small, but Sinclair took a very, very long time before he gave up this idea.   I saw 'Pandora', a briefcase-sized prototype, about a year ago. It used the flat screen and magnified it by using a concave mirror. Holding your head uncomfortably steady in front of this box, for all the world as if watching an old-fashioned 'What the Butler Saw' peepshow on Brighton Pier, you saw green letters, 20 char- acters per line on 12 lines, floating eerily off at an infinite distance.   The software was vaguely sup- posed to be CP/M and Spectrum compatible, and there was supposed to be some way of plugging it into a full-scale display. There were no disks, and the idea was to use an Astron card - credit card sized, with electrical connectors and embedded memory chips - instead.   This idea has been retained, but only in outline. It has been modified in the actual machine because of the problems anticipated from the card's exposed electrical connectors. 'We wanted protected contacts,' said Sinclair, 'so we had to devise our own package for add-in chips.'   The correct word to describe the original Pandora was 'disaster'. It

was heavy, much too thick, and the display was unusable. The software was never finalised. Fortunately for the world, the costs of liquid crystal displays were dropping like lead on a neutron star. By the time Sinclair Re- search was sold to Amstrad, it was obvious to everyone that the econo- mic advantages of the flat screen were disappearing, and no-one would have to justify dropping the strange design.   When he bought Sinclair Research, Alan Sugar also bought the rights to Pandora. I asked him if he was going to launch it. 'Have you seen it?' he asked shortly. 'Yes,' I said. 'Well, then.'   Free from the need to justify years of hard work on the flat screen, Clive decided to buy an Epson 100-column LCD display and build his system around that. His two main objectives were price and weight. 'Computers at present are a compromise,' he said when describing this new machine. 'They are either not portable, or not comprehensive. This one is highly portable, and it should do everything you want a personal computer to do. That means you have to do a rethink - you can't put in disks because that slows you down and increases the weight.' Hardware The machine is the size of an A4 sheet of paper, and at 2cm is pretty thin. It has a standard qwerty keyboard, described by Sinclair him- self as AT standard for reasons that have more to do with wish than ful- filment. However, he's right about one thing: a portable has to have a quiet keyboard. With four or five people in a lecture clattering away on standard keyboards, the device would quickly be banned from public events. Unfortunately I didn't get to see the prototype or pre-production keyboard, so I can't tell you whether this objective has been reached. Nor do I know if anything was sacrificed to provide it.   Above the keyboard is a display made from 'super-twist' high- contrast liquid crystal. This is not backlit, but is very readable in nor- mal light. It is divided into four win- dows, with the central 80-column window providing a conventional character display. On the left is a menu window of 106 characters; on the right is a map of the whole page, showing 64 lines of text. One pixel represents each character of text. Further to the right, the last window shows machine status.   Underneath the space bar, under a smoked acrylic panel (at least, that was the plan) are three slots. 'These give the function that disk drives nor- mally give,' said Sinclair. Well, sort of: they are actually memory expan- sion, but since you can plug in permanent memory and erasable

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permanent memory as well as RAM, you can think of them as being vaguely disk-like if you prefer.   The 'disks' themselves measure .2cm square by 1cm deep. Normally such tightly packed memory chips would overheat, but at the low pow- er consumption of this machine, I don't expect that kind of problem.   Under the display there's a socket for an RS232 plug. There is no para- llel printer socket, so the RS232 must be used for modem communications and printer operation; obviously this rules out the idea of downloading text from a bulletin board direct to the printer. This port is also used for a pseudo-disk operation called PC Link   On one side there's an expansion plug, providing third-party builders with the opportunity to build odds and ends like parallel printer drivers, mouse drivers, microdrive interfaces and other whimsies. A very hard-to- locate reset button is buried deep in the heart of the machine, reachable only with a strong, thin piece of wire. (Sinclair really doesn't want you to restart the machine once it is going.)   Inside are the Z80 processor, the custom logic chips, a minimum of 32k of static CMOS memory, a tiny loudspeaker, and a big-capacity one- Farad capacitor to keep the machine going for two minutes, when you change batteries. Underneath is the socket for four pencell batteries, pro- viding 20 hours work. That doesn't mean you have to change them ev- ery day - you have to use the Z88 for 20 hours. Software The main program was devised by a Cambridge outfit called Protech, under the name Pipedream. it is a spreadsheet with rows and columns usable as text pages. Underneath Pipedream, or perhaps side by side with it, are other utilities, all built into 128k. They include a diary/ calendar, a note storage (database) system, and a programming lan- guage - BBC Basic. They will also include a crucial extra - PC Link. Extra programs can be loaded physi- cally by plugging in cartridges con- taining the code.   Here we come to two unknown factors. One is the operating system; and the other is the problem of keep- ing it going when people plug things in. First is the question of why the system runs other programs. Until independent software houses have seen the machine operating system (MOS) and attempted to create their own programs to work with it, there is no way of knowing how powerful it is. Nor is there any way of knowing how reliable it will be - and it really

The Z88's display is divided into a number of windows. From left to right these show menu and command options, the current document, a map of the page layout represented as one pixel per character, and system messages. The vertical bar on the map shows the current window's position in the whole document Pop-up desk accessories such as a calendar, diary and calculator are provided. The symbol in the system info column on the right of the display indicates that the battery power is low. The line numbers and column letters reveal that all documents are essentially different uses of spreadsheets does have to be reliable. This is be- cause, in theory at least, it never stops and the machine is never switched off. Dozy concurrency All the units of the machine are codenamed Dozy. There is Dozy Pipedream, Dozy Calendar, Dozy Ca- culator, and Dozy Database - all trying to save battery power by going to sleep as often as possible. Sinclair himself describes the machine as working in 'concurrent' mode, but he is using he word in a different sense from most. What Sinclair means by concurrent is that the processes are put into stasis when you switch context so that you don't close down the word processor to run the diary.   'In principle, you can have any number of programs and switch be- tween them with the status of each being saved,' he said. 'We think this is essential in a portable, so you can look up a number in your phone list while working on the word proces- sor, and so on.'   This isn't what Digital Research (as one example) means by concurrency. With Concurrent PC-DOS DR pro- vides a system where your word pro- cessor continues functioning while you run he phone list. Anything that was going on continues: it will carry on searching for a word, for instance, or it will carry on reformating text, or it will carry on printing, or it will car- ry on waiting for you to press a key.   Sinclair's system is something else - something I'd call a context switch. As with most RAM-resident PC programs, his applications halt and stay resident in their own seg- ment of memory when another prog- ram is invoked. The MOS's job is to make sure it knows which applica- tions are using which bits of mem- ory, and where they are keeping their data. The other thing it has to do is restart the system when something funny occurs - for example, when someone plugs in a program or data module. Mostly, however, it will be sleeping.   In order to save battery power, the MOS watches for any sign that someone isn't using the computer - and halts it. It turns all the memory into standby mode, using virtually no power, and blanks the display.   The combination of these two re- quirements bothers me, and I really

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sequences of characters have to be typed in; they're given on the menu.   Well, we'll see. In the meantime, I'm delighted to be able to say that an awful lot of WordStar commands have survived, and WordStar-trained typists will be able to delete lines with control-Y in a delightfully famil- iar way.   More important than all this is the fact that you can see, from the map on the right exactly where you are on the page, In principle I think the map is excellent, but I'm not happy about having only 80 columns. I know I can make notes on a screen of that size because the Tandy 102 has a screen of 8 lines add 40 char- actors. And people who use Word- Star with full Help and double spac- ing tend to have the same amount of text onscreen.   But I can't easily read a document on that. As you adjust the text, the map changes. But in order to keep up with typing, the map doesn't try to redraw itself until you stop typing for at least a second. There's a simi- lar delay when reading.   Experience will be the only proof of the theory that the map will make document reading - skimming through after writing something counts as reading - as easy as Sinc- lair's designers believe. The simula- tion I saw, on a BBC Micro, was un- fortunately too slow to give a real indication of what it might be like, and I'm going to reserve judgement, heavily. Diary The main reason why no-one has ever seriously used a computer diary is very simple: whenever you are in a situation where you are trying to set up an appointment, you tend not to have the computer with you. A key factor in the design of the Dozy Diary is the fact that the machine which contains it is so small and light, you might well take it with you, even on social visits. Tucked away in a briefcase, it will be there to inform you that you can't make the date for Thursday because you have to take the dog to the vet.   The diary is nice, and doesn't do the daft things that lots of computer diaries do: you can make any appointment for any time, and set the alarm for any other time. And you can categorise appointments, and list all appointments for a certain category.   The diary is actually just a free- form database, capable of holding a limited amount of ASCII text. The limits depend on how much RAM you have in the system. Coupled to it is a calendar which looks through the diary database for alarms, markers and times. If all it finds is gossip, it will ignore it. But if it finds that there is a time corresponding to the time held in its real-time clock, it will

sound the alarm.   The calendar itself is beautifully simple, showing a month, and link- ing you to the appropriate part of your diary when you move from day to day or week to week. Cursor keys make this very intuitive. Calculator The calculator was undergoing final revisions when I saw it, but appeared to be a simulation of a standard, un- complicated pocket adder. If the de- signers can find a way of saving me from having to use the Shift key for some of the functions, I might even use it occasionally. (The design team were fairly sure this would be incor- porated in the final version.) PC Link Can I be a little boastful here? This one was my own idea. When I first saw the machine, I took exception to the idea that you didn't need disks. You do, not just for routine storage and saving of programs and data, but also for the simple reason that other people often give you disks with information on them.   'Why not sell a disk and a cable,' I said, 'which effectively turns any IBM PC into a disk drive?' For £15-odd, that's exactly what it does. Versions to work with other well-known com- puters are likely, some from Cam- bridge Computer, some from third parties. Expansion The theoretical range of expansion is infinite. In practice, the internal mem- ory limit is 1Mbyte (and not until the end of 1988 will there be hardware to do that) and the theoretical plug-in expansion is 4Mbytes, which is even further off.   'There will be a modem, very small, plugging into the phone sock- et,' predicts Sinclair. 'But we're still not sure we can do a Hayes- compatible device for £100.' But that, obviously, is the price he is aiming for. Price The machine with 32k costs £200, less five pence, plus VAT. Upgrading it by plugging in 128k of RAM costs £50. An extra 32k is cheaper at £20 (the usual five pence and VAT all along, by the way). PC Link costs £15. Conclusion At the price, if this works, I'd buy a Z88. It really is important, if you are carrying a machine around, that it is light. I use a Tandy 102 not because it has the functions I need, but be- cause it's the only machine which doesn't break my back at exhibitions. But even that is more weight than I'm comfortable with.   The Z88's screen map is a great solution to the problem of the limited display. My own preferred solution would be to have a socket from which a full-screen composite video output could be taken, Sinclair says this isn't possible,   The spreadsheet is good enough to be used in board meetings by people who want to do more complex cal- culations than could be done on pap- er with a calculator. Sinclair himself thinks it is all the spreadsheet that anyone will ever need, and while it's true that most people barely use five per cent of their spreadsheet power, I think he's being over-optimistic.   The text editor is fascinating and I think I'd be able to use it - for note- taking. I'd like a parallel port, but I'll settle for a link to the next PC as a pretty good option.   My overall impression? If it works, it could be something new in a mar- ket that hasn't been properly ex- ploited. I expect Sinclair to sell at least 20,000 in the UK in the first year if he can build them, and he could even sell ten times that if he gets his marketing right.     END

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