[COFF] What Happened to Interdata?

[Greg 'groggy' Lehey]

On Thursday, 27 July 2023 at 16:33:54 -0400, Paul Winalski wrote:
> On 7/27/23, Noel Chiappa <jnc at mercury.lcs.mit.edu> wrote:
>
>> Someone who's familiar with the 360 instruction set should be able to look
>> at e.g.:
>>
>> and see how compatible it is.
>
> Interdata has some data types and instructions for manipulating them
> not present in S/360.  Circular lists, for example, and instructions
> for CRC calculation.

Yes, it's possible that both Interdata and RCA/UNIVAC/ICL instruction
sets are supersets of the /360 instruction set.  The only one I still
remember is the LI (load immediate) instruction.  The /360 did the
same function with LA (load address), but IIRC that was RX (4 bytes),
while LI was RR (2 bytes).

> I didn't see anything about packed or zoned decimal support.
>
> So perhaps an extended subset of S/360.  I'd have to do a side-by-side
> comparison between this document and S/360 Principles of Operation to
> determine the level of binary program compatibility, if any.  But it
> looks like it might be better than the HitchHiker's Guide to the
> Galaxy adage:  "almost, but not quite, entirely unlike tea."

Yes, that seems reasonable.  My guess was that binary compatibility
wasn't a big issue in those days, since nearly all applications
software was written only for specific installations.  And of course
licensing issues would preclude running IBM OS on the other machines.

Greg
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