[COFF] Re: What Happened to Interdata?

On 7/25/23, segaloco via COFF <coff(a)tuhs.org> wrote: I suspect that Interdata had the same problem with their S/360 lookalikes that RCA did with theirs. If your business model is to provide a cheaper hardware alternative to IBM, your machine has to run IBM software, particularly the OS. When IBM did their pre-release of the S/370 specifications they deliberately left out key bits of the privileged architecture, such as the detailed bit layout of the PSW. Companies such as RCA and Interdata had make guesses while designing their S/370 lookalikes and in some cases they guessed wrong. RCA's Spectra 70 couldn't run IBM OS/VS or DOS/VS and that made it a total non-starter for most IBM commercial shops. I suspect Interdata ran into the same problem. Yes, they could design their own me-too operating systems, but they would always lag behind on new IBM OS features, on which critical IBM applications would depend. The IBM customer base knew this and stuck with genuine IBM. A lower price point wasn't enough to make up for the incompatibility. The advent of 32-bit minicomputers at the end of the 1970s brought down for good the IBM price umbrella under which Interdata and other lookalikes had been living. An example of how high that price umbrella had been: In 1978 my undergraduate alma mater was a true-blue IBM shop with a S/370 model 125 running batch, CICS, and a small BASIC timesharing system for the students. They'd outgrown the model 125. IBM's solution was to upgrade to a model 135. For the same price as the IBM processor upgrade, DEC was offering a complete VAX-11/780 system to run timesharing and other academic computing, with the S/370-125 devoted exclusively to the business side of things. The 11/780 was roughly equivalent in computing power to an IBM S/370-158--two models up from the 125. Buying the 11/780 was a complete no-brainer. IBM was forced to cut prices on the S/370 line, and that fatally destroyed Interdata's one advantage over true S/360/370. -Paul W.