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From: news@ism780c.isc.com (News system)
Newsgroups: comp.arch
Subject: Re: IBM 7094 II
Message-ID: <50926@ism780c.isc.com>
Date: 29 Nov 90 23:15:51 GMT
References: <9011272349.AA25956@ucbvax.Berkeley.EDU> <12073@life.ai.mit.edu>
Reply-To: marv@ism780.UUCP (Marvin Rubenstein)
Organization: Interactive Systems Corp., Santa Monica CA
Lines: 41

In article <12073@life.ai.mit.edu> tk@rice-chex.ai.mit.edu (Tom Knight) writes:
>This machine had approximately a 5 microsecond instruction time for
>simple (clear accumulator) instructions.  For floating ops, I think
>the time was more like 12-17 microseconds.  It used sign/magnitude

The 7094 manual in front of me indicates that on average integer operations
(add, sub, and, etc) requires about 3.2 microseconds.  4.0 microseconds is
the worst case time.  Floating add was from 4 to 24 microseconds, floating
multiply was from 4 to 10 microseconds.  The speed of the 7094/II was a
little greater but not by much.

>arithmetic and had a peculiar notion of a "logical" accumulator
>(unsigned) and an "arithmetic" accumulator which included a sign bit.
>These registers shared 35 of the 36 bits, only the MSB differed.  CLA
>cleared the arithmetic accumulator, CAL cleared the logical
>accumulator

There was only one accumulator.  There were two types of operations on the
accumulator.  It was analogus to signed and unsigned of C.

>              The machine had some very specialized instructions,
>highly non-Risc like, such as TRQ (translate by replacement from MQ)
>which could be used (it was said) to make COBOL more efficient.  It
>was a predecessor of the 360 Edit and Translate instructions.

Actually the opcode name is CRQ (Convert by Replacement in MQ).  This was not
for the benifit of COBOL.  The instruction existed before COBOL.  The machine
was originally programmed largely in assembly language.  CRQ and and other
similar instructions were provided for converting BCD to binary and back as
well as for other tasks like leading zero supression (replace leading zeros
with blanks) in a BCD representation.

>The major programming languages were MAD (Michigan Algorithmic
>Decoder), Fortran II, and FAP (Fortran Assembly Program).
>
>For all you FAP programmers out there: TSX $EXIT,4

Late in its life IBM supplied an operating system called IBSYS.  IBSYS
provided FORTRAN/IV, COBOL, and MAP (Macro Assembly Program).

    Marv Rubinstein -- 7094 mavin