15 Jul
2015
15 Jul
'15
10:48 a.m.
Lots of machines supported variable length operands (like the machine
you reference in the link, IBM S/360, Burroughs, etc. etc. However,
machines with variable length instructions not split into any kind of
word boundary are not as common.
This isn't about whether a machine was good or bad / worse or better /
or even level of historical interest. Just whether or not it was
interesting - in particular interesting to me. If the CDC machines like
that interest you, by all means have at them. ;)
I note that, there isn't enough information in that manual to do what I
plan to do for the IBM 1410 - reproduce the actual machine logic.
Compare/contrast what you referred to to the documents at:
http://bitsavers.informatik.uni-stuttgart.de/pdf/ibm/1410/drawings/
On 7/15/2015 12:10 AM, Chuck Guzis wrote:
On 07/14/2015 09:16 PM, Jay Jaeger wrote:
Other than clones and the like (e.g., from folks
like Honeywell), I'm
not aware of any other machines with a similar architecture to the 1401
and 1410. Name them?
Well, how about a bit-addressable, variable field length machine that
had not only your basic set of floating point operations, but also
variable-length binary, binary modulo-256 and packed BCD to a length of
65535 bytes (131K BCD digits)? Circa 1969-1971:
http://bitsavers.informatik.uni-stuttgart.de/pdf/cdc/cyber/cyber_200/602560…
When you've got a few minutes to spare, try writing the VHDL for it.
This was a Jim Thornton design, later taken over by Neil Lincoln. Later
versions of the machine had drastically reduced instruction sets from
the original, culminating finally in the liquid-nitrogen cooled ETA-10.
But really, variable-word length machines, while they made efficient use
of storage, were pretty much limited to a character-serial
memory-to-memory 2-address organization. Quaint and perhaps
interesting, but doomed from a performance standpoint.
--Chuck