The Quick IDT Guide

Integrated Device Technology, Inc., is a manufacturer of a variety of integrated circuits and special-purpose electronics components, many of which find their way into use in personal computers. Yet to the general computing populace they are known only (if at all) as IDT, former maker of the WinChip microprocessor. The WinChip series were IDT's only x86-compatible products, although they also produced a variety of MIPS-compatible processors. Like several other companies, IDT released a brief run of x86 products before deciding to exit that market. Their x86 design unit, Centaur, was sold off to VIA in 1999. Unlike some of those other companies, IDT was involved in several other markets, where it continues to compete.

The History

IDT as a company was founded in 1980. IDT is a diversified silicon company; they produce a variety of ICs used substantially in implementing different communications links. The Centaur design unit was formed in 1995 as a "stealth start-up", owned entirely by IDT, to design x86-compatible microprocessors.

IDT was in a better position than many of the companies that had an eye on the x86 market. It had its own wafer fab, in Oregon, as well as contract manufacturing deals with foundries. It was a major player in other, more stable, markets, which gave it other sources of revenue and more ability to survive fluctuations in the CPU market.

From the beginning, IDT positioned its products as entry-level parts or upgrades for existing Socket 7 motherbaords (of which there were many). IDT's products were easy drop-in replacements for most Socket 7 systems, and essentially delivered the performance normally reserved for Super 7 processors to the cheaper, older socket.

Overall this was a similar strategy to what Cyrix, Rise, and to a lesser extent AMD were pursuing. Conquering a piece of the lower end of the market was much easier and much cheaper than trying to go directly toe-to-toe with Intel's flagship products. Crucially, this was a part of the market that Intel seemed uninterested in, leaving room for the smaller players to stake a claim.

The first generation of products was technologically sound, but prices were initially somewhat high and supply was constrained. Unfortunately, subsequent generations did not scale quickly enough in either clock speed or instructions per clock, and so were soon left behind in the performance race. And as the number of Socket 7 motherboard owners looking for processor upgrades began to dwindle (particularly as buyers saw that they could step up to a significantly more robust Slot 1 or Slot A processor), that market disappeared.

IDT probably could have continued to carve out a decent niche in low-end systems were it not for the introduction of Intel's Celeron. Competing with the Celeron was a major challenge, and IDT simply couldn't do it.

In July 1999, IDT announced that it was getting out of the x86 business, and by that August it had announced a deal in which VIA would acquire Centaur and all related intellectual property. Centaur lives on still, operating mostly independent of its new parent company. Every VIA microprocessor is essentially a Centaur design; athough VIA acquired the remains of both Centaur and Cyrix's microprocessor teams, it essentially disassembled Cyrix and kept Centaur intact (and in the same building). VIA's first generation microprocessor was in effect a WinChip 3, and subsequent generations (up until the VIA Nano) are derivatives of that design.

The Technology

The Centaur design philosophy was fairly straightforward: optimize for a small die size and low power usage, tolerating some tradeoffs in performance. Although the chips used Intel's complex x86 instruction set architecture (which is, after all, the canonical example of a Complex Instruction Set Computer architecture), internally they were very simple and stuck closer to the design philosophy of a RISC design.

The WinChip series were in some ways more technologically similar to a 486 than the contemporary that they fought against: they were single-pipeline (that is, scalar), in-order designs (the competing Pentium was super-scalar and in-order; the K6 was super-scalar and out-of-order). Although the WinChip missed out on any performance improvements it might have gained from incorporating super-scalar or out-of-order execution, the complexity savings were substantial. The WinChip die was small and, because of its reduced complexity, comparatively easier to design, debug, and test.

Centaur kept things simple everywhere they could. The integer pipeline was 4 stages to the K6 or Pentium's 5 stages. Like the K6, but unlike the Pentium, the floating-point unit of the original WinChip was not pipelined at all, which would have damaged performance in the relatively few applications of the day that relied heavily on the FPU. In the WinChip 2, the FPU (and MMX and 3DNow! execution units) was pipelined.

WinChip products launched with support for the full x86 instruction set including Intel's MMX extensions; the WinChip 2 added support for AMD's 3DNow!.

The Products

The first Centaur-designed products came to market in 1997. The WinChip (codename C6) was launched in several speeds that put it more or less on par with its competitors. Although the WinChip design was clearly intended to surrender some performance in order to optimize other factors (most notably, cost), the first generation of WinChips were able to stand on a roughly equal footing with the rest of the market.

In 1998, IDT released the revised WinChip 2 (written variously as WinChip2, Winchip 2, WinChip/2, and all sorts of bizarre permutations, but IDT's press releases used WinChip 2). The WinChip 2 (codename C6+) added new silicon to support AMD's 3DNow! instructions (IDT seems to have originally intended to market a WinChip 2-3D with the instructions enabled and a separate "vanilla" WinChip 2 with them disabled), and offset the modest increase in die size by moving to a smaller manufacturing node. Despite the die shrink, the WinChip 2 did not come in much faster frequencies than its predecessor, and so even with its other improvements it was now well behind the performance curve.

1999 brought the slightly revised WinChip 2A (also codenamed C6+), which was notable mainly for its faster Front Side Bus speeds and, to cope with the new bus speeds, unusual choices of multipliers. Unfortunately, these multipliers were needed to ensure the new chip ran at essentially the same core clock as the older chips; in terms of clock speeds, IDT was treading water. By this time, the market was leaving them behind.

The WinChip 2B (still bearing the codename C6+) was supposed to come next, but it was not to be (if you will forgive the pun). The 2B made it to the point of engineering samples appearing in the wild before IDT announced in July 1999 that it intended to get out of the x86 business. A WinChip 3 was also in the pipeline at the time and also canceled, but essentially re-materialized in the form of VIA's Cyrix III.

Editor's note: This article is part of the expansion plan for the Big Processor Guide. It will make a lot more sense in the near future.

  • RSS feed StumbleUpon Digg Yahoo! My Web 2.0