Talk:IBM 801

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History of the 801 ISA and of implementations of it

Latest comment: 5 years ago2 comments2 people in discussion

System 801 Principles of Operation, Version 2 describes a byte-addressable machine with 16 24-bit GPRs and a mix of 16-bit and 32-bit instructions.

Other papers speak of a machine with 32 32-bit GPRs and 32-bit instructions.

ROMP is described by IBM as "a single-chip derivative of the 801 processor project of IBM Research"; it started out with 16 24-bit registers, went to 16 32-bits registers, and had multiple instruction lengths.

So are there any references for:

the different versions of the 801 instruction set;
the implementations of those versions of the instruction set, whether in the form of simulators or actual hardware? Guy Harris (talk) 01:46, 18 January 2019 (UTC)Reply

Microprocessors: A Programmer's View (1990) by Robert B.K. Dewar and Matthew Smosna says on pp 263–264 that there were two versions of the 801: the original with 16 24-bit GPRs and 16- and 32-bit instructions, and a later one with 32 32-bit GPRs and 32-bit instructions. They say in later chapter that the ROMP was based on the original version of the 801. IIRC, the IBM J. Res. & Dev. paper "Evolution of RISC Technology at IBM" (IIRC, this is the title), which is available for free from the IEEE Xplore Digital Library, also says that there were two versions of the 801, but it doesn't give nearly as much detail as Dewar and Smosna. 99Electrons (talk) 22:25, 13 March 2019 (UTC)Reply

Did IBM try to commercialize the 801?

Latest comment: 5 years ago1 comment1 person in discussion

In Computer Wars: How the West Can Win in a Post-IBM World on p. 49, IBM is said to have tried to commercialize the 801 as something that could emulate and outperform various IBM minicomputers and low-end S/370s. The book goes on to say it was eventually cancelled because emulation imposed too great a performance penalty for it to work. Is the project described in this book (code-named Fort Knox) related to the IBM 9370 low-end S/370 mainframes? (IBM says the 9370 uses some sort of 801-derived processor to emulate the S/370 architecture). 99Electrons (talk) 23:40, 25 February 2019 (UTC)Reply

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