NexGen Microsystems Inc, the Milpitas, California-based technology company, recently wowed the microprocessor community with the announcement of a chip set that offers not only the performance of Intel Corp’s Pentium processor, but also 100% compatibility with it. Drifting out of the hotel, dazed journalists – inspired by the accompanying announcement that IBM Corp was to be making the chips – wandered whether this could be the final nail in the coffin for the Pentium. In retrospect, probably not. Let’s look at the history of NexGen, along with the technical aspects of the chip and the firm’s marketing strategy. NexGen was formed in 1986, as a technology company initially trying to develop multiprocessing systems and processors. Shortly afterwards, it dropped its commitment to hardware and concetrated solely on developing iAPX-86-compatible chip sets to rival Intel. This is no mean task and requires a lot of money, which it raised over the next few years from institutional and trade investors including Compaq Computer Corp, Ing C Olivetti & Co SpA, Harvard University and ASCII Corp. Initially, it developed the F86 chip set, which comprised eight parts and was designed to execute the 80386 and 80486 instruction sets twice as fast as the 80486 could. It would use a 64-bit bus, the NexBus, to shift data around faster.
Undeterred
It eventually had the thing ready in mid-1991, but by that time, the market was too far advanced for it to make any money and it was never marketed. Undeterred by this, the firm went on to try and catch hold of the fifth generation processor market, in the form of a Pentium-compatible processor. NexGen obviously had too much ploughed into the F86 to give it up now, so it decided to carry out its research on the back of its existing architecture, including the NexBus. That’s how it arrived at the launch of its NexGen Nx586 chip set earlier this month (CI No 2,373). The chip set, which will be available in 60MHz and 66MHz versions, has been squeezed down from its original eight chips to a compact and bijou two: the central processing unit itself resides on one chip, and the system logic on another. The floating point unit has been stripped out onto a third chip to become optional. This is because NexGen believes 98% of personal computer applications to be integer-based. In place of the floating point unit on the CPU, NexGen has put an integrated Level 2 write-back cache controller, which links into the external Static RAM chips at full speed along with the level one cache controller. The Level 2 controller offers 256Kb or 1Mb, while the on-chip cache offers 16Kb instruction and 16Kb data capacity. In other high performance x86 RISC processors as NexGen’s blurb politely puts it, the Level 2 cache and memory controller are contained on a separate chip, which slows down operation. This is all very well, and indeed gives the chip set performance that allegedly exceeds the Pentium. The problem is that the chip is held back by the 64-bit NexBus, which the firm admits was originally designed for multiprocessing applications, and is thus not optimised for single-chip operation. This means that in practice, the chip will be virtually indistinguishable from Pentium in terms of performance.
By Danny Bradbury
On a logical level, the NexGen chip set works by taking x86 instructions, and feeding them into a decoder and scheduler unit. This converts the instructions into commands using the chip set’s own RISC architecture, RISC86. This then lines them up and feeds them out into multiple execution units, which can be increased in number to enhance performance. The company claims that the RISC86 instructions are specifically designed to support the x86 instruction set while obeying RISC performance principles and are therefore much simpler and easier to execute than complex x86 instructions. NexGen is talking about producing processors with more execution units in the future. The internal structure of the chip includes many renamable registers, which can be used to handle the instructions more effectively acco
rding to NexGen. Features of the chip include superscalar execution and branch prediction, both of which the Pentium has. The CPU will be available in both 60MHz and 66MHz versions in the second quarter, according to the firm, for $460 and $506 respectively. The floating point Nx587 chip, again in 60MHz and 66MHz models, will ship in the middle of this year for $128. These prices are in quantities of 1,000. The system logic chip for Vesa local bus and AT standard buses will cost $86. The price of a 60MHz CPU with floating point and system logic will therefore be $674 – not even $100 less than the Pentium with the accompanying PCI chip set at Intel’s second quarter pricing. Given its different pin-out technology, the NexGen Nx586 needs a different motherboard design, meaning that the firm will need a lot of marketing clout to shoehorn the processor into the market. NexGen has signed seven Taiwanese motherboard manufacturers to make boards that will use the chip: DataExpert, Micro-Star International Co, Chaintech Computer Co Ltd, Abit Computer Corp, WIN Technologies, Seritech Enterprise Co Ltd and GIT Co. The firm originally said that IBM would be manufacturing the chip at its Burlington, Vermont plant, (where it is making its PowerPC and 16Mb DRAM chips), using a 0.5 micron process. Containing up to five layers of metal interconnect, the chips, manufactured on 8 silicon wafers, would have used IBM’s flip-chip C4 packaging technology, whereby the silicon die is attached via solder bumps within the die. Herein lies one of the main problems with NexGen: one day after the press briefing, the company called and said At the current time there is not a manufacturing agreement between NexGen and IBM… we kind of jumped the gun on that. The sound of rapid backpedalling is not only embarrassing for NexGen, but also all too frequent. The firm was originally involved in both multiprocessing system boxes and processors in 1986-8, and then it dropped the system hardware.
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Now it has made a complete U-turn and abandoned the multiprocessing idea altogether, saying that it can make its money in selling the chips to third tier manufacturers – the type of manufacturer that is well known for price as opposed to quality or marketing expertise, and the type of manufacturer that has been going bust in the UK for the past three years with depressing regularity. The firm’s current position is thus: it hasn’t produced any revenue in its eight years of existence, but has garnered $90m from its institutional investors, of which only $30m is left. It is in a position where it has announced a product and a shipment time, and is waving around undertakings from US personal computer manufacturers Tangent Computer Corp, Burlingame, California – promising a fully-configured $2,000 system based on the Nx586 processor with 8Mb, 340Mb disk with local bus interface, local bus graphics accelerator, 14 1,280 by 1,024 monitor, Windows for Workgroups and MS-DOS 6.2 – Adisys Corp, Santa Clara, and Compu-Tek International Inc and Lucky Computer Co, both Richardson, Texas – but NexGen has no-one to make the chips in volume yet. And at the time of writing, neither Olivetti nor Compaq – both big shareholders in NexGen have made any commitments to take the chips. Bearing this in mind, along with an uncertainty as to whether the chips will actually appear in the second quarter despite NexGen’s protestations to the contrary, the jury is still very much out on the prospects for the company – and talking of juries, there’s always Intel’s legal flak to worry about.
