Super-skinny operating system king Tao Systems Ltd of London was at CeBIT showing release 1.28 of the Taos distributed operating system running on the PowerPC, and saying that version 1.29, due in a few months, will support OpenFirmware-compliant PReP systems, with a version for the Macintosh set to follow early this year. For those that are unfamiliar with Taos, it sounds like an impossible dream: an operating system that runs across heterogeneous networks of processors, does so blindingly fast, and takes up about as much memory as 8-bit CP/M. Moreover applications do not need to be recompiled to run on a new processor. It gets stranger. The secret to the operating system’s processor-independence is the fact that Taos applications, and indeed the operating system itself, are compiled into code for a ‘Virtual Processor’. This Virtual Processor code is shuttled to the processor on which it is to run, and is translated on the fly into that processor’s native binary code. It sounds as if it should be a deathly slow process, but practice shows that in fact Taos is very fast indeed – currently the operating system is picking up interest from games, set-top box and telecommunications companies. In addition, the Taos designers boast that the only code ever loaded into memory is code that will be executed, and the whole thing is executed as a fine-grained series of objects.
Virtual Processor
It makes the question ‘how big is the operating system’ virtually meaningless, since the answer is always ‘exactly as big as it needs to be’. The operating system core, however takes up about 10Kb. Implementing Taos for a new processor entails writing a new translator to convert Virtual Processor code to the native binary. Currently six implementations are completed and available: Transputer; native Pentium; PowerPC 601 and 603; Advanced RISC Machines Ltd ARM; MIPS Technologies Inc R3000 and Hitachi Ltd’s SH7000 processor – the intellectual property remains with Tao, but this implementation was paid for by Hitachi, whose proprietary RISC turns up in Sega Enterprises Ltd’s games machines. Three more: MIPS R4000, Alpha AXP and Motorola 68000, are under way. It took five man-weeks to get the initial 601 translator up and running, says Francis Charig, who heads Tao Systems. The subsequent 603 variant took only a couple of days. Currently, version 1.28 does not boot PowerPC Reference Platform machines, so the PowerPC has to sit on an expansion board in something such as an iAPX-86-based personal computer. However, as previously mentioned, the operating system is scheduled to become PReP-compliant in the next release. The Macintosh version is, not suprisingly, more problematic, since the team has to negotiate the maze of Apple Computer Inc’s proprietary subsystems. As we’ve reported in the past, quite a few freeware Unix initiatives have foundered on this particular rock. However the team is still confident that Taos will be running on Macs by the end of the year. For end-users, Mac Taos may well be bundled with particular applications, to be invisible (in much the same way that Doom on the iAPX-86 personal computer comes with its own operating system). Developers will get a more conventional operating system environment. When we first saw Taos back in 1993, we were faced with a stark choice – was it a work of genius, or was it all smoke and mirrors? A couple of years later, exhibiting by invitation on the Motorola Inc stand, Francis Charig still can’t name the large Japanese computer, European telecommunications companies or US set-top box manufacturers that he says are so keen to use the operating system since they demand confidentiality. Still, with around 40 full-timers developing the system, and a turnover of $20m last year (up from approximately $0 the year before) we’re confident that this is still one of the most exciting (and more importantly, practical) operating system advances around. As for Charig and his team, well the main worry that they expressed when we talked to them this time was that Taos might not scale ve
ry well beyond 1.93m – that’s million – processors! – Chris Rose (C) PowerPC News – Free at add@power.globalnews.com
