No, the evolution of the S-100 market was really quite different from that of the IBM-PC market. The longer the S-100 was allowed to progress on its own, board vendors, with the notable exception of Godbout/CompuPro, who really never even guaranteed his boards to work with others of his own manufacture, tended to make their products more and more interoperable, as the market demanded it. It was a terrible overhead for them to buy back boards that wouldn't work with a customer's other equipment, so they made every effort to get around that. The proposal of a "standard" with the "optional" features they managed to put into it, put a quick stop to that. Most of the board makers had worked out most of the interoperability issues by that time, and the development of a standard offered them an opportunity to reverse the process, forcing their customers, foolish enough to believe their marketing line suggesting some sort of superiority or other, to buy new boards, all from the same manufacturer. This meant that whereas one previously used a CCS CPU and FDC, SD Systems' RAM, and TEI's I/O board, now one had to have boards with the same maker's trademark. In the case of CompuPro, the trademark wasn't enough. One had to have boards with the same series number, and, in some cases, the same manufacturing date, or they couldn't be relied upon to work together. One had to cope with the fact that some boards required a bus signal be grounded while others required it be tied high, while others yet required it be left floating or have a specific signal on it. The technical discussions in the standards committee meetings quickly deteriorated into discussions over which features should be mandatory and which should be optional. When the standard was adopted, it really wasn't a standard at all, since so many features, labeled optional, when implemented in accordance with one alternative, could cause another maker's product, equally compliant with the standard, to malfunction to such extent that it or the entire system didn't function. Once the standard was adopted, and by that I mean within weeks, the S-100 bus was a dead duck. From that point forward, the only way to ensure a set of boards complied with the same standard was to buy the set at the same time, from the same retailer, with a warranty to assure the buyer that the boards would work together. Of course one quickly learned he was high and dry as far as other products were concerned. The PC market started with a firm standard, however goofy (e.g. positive-going interrupt and reset signals on the bus, etc.) that, when faithfully adhered to, worked pretty much all the time so long as one didn't tamper with it. Once IBM, with its massive influence on the market (at least back then) set a standard, 3rd party manufacturers knew they had a large enough market for products that worked on that standard, and, frankly, they could live without IBM's competitors. Now that IBM is really of no further interest in the market, like every other large corporation that's attempted to assume the role of Mr. BIG on the market, nobody sets the standards, hence there's no penalty for failint to adhere to the standard/convention/whatever, that drives the design of new products. A typical example is the 64-bit PCI. I've seen several desirable cards offered for the 64-bit PCI, yet I've not seen even ONE advertised motherboard that actually supports 64-bit PCI. From what I've read, 32-bit PCI boards work in a 64-bit slot, yet nobody seems to be offering that feature in their advertisement. I'd guess that's because it's cheaper/easier to diverge slightly claims about compatibility. It's all about money, after all. Dick ----- Original Message ----- From: "M H Stein" <mhstein(a)usa.net> To: "'ClassicComputers'" <classiccmp(a)classiccmp.org> Sent: Sunday, October 28, 2001 9:13 AM Subject: Re: VLB SCSI? either, not to mention that everything else was proprietary at that time (not to mention IBM's infamous Slot 8, PS/1's and MCA, non-standard memory modules, etc.)... need one, or a complete PSU (especially an odd-sized one) or anything else for an old PC, drop me a line. could evolutionary