Re: Why VAX Was the Ultimate CISC and Not RISC

Thomas Koenig <tkoenig@netcologne.de> writes:

Anton Ertl <anton@mips.complang.tuwien.ac.at> schrieb:
>

Have TTL chips advanced between the VAX and the first HP-PA
implementation?  I don't think so.

>
Oh yes, they did; there were nine years between the launch of the
VAX and the launch of HP-PA.

So what?

and you can see pictures
at https://computermuseum.informatik.uni-stuttgart.de/dev_en/hp9000_840/

Nice!  The pictures are pretty good.  I can read the markings on the
chip.  The first chip I looked at was marked 74AS181.  TI introduced
the 74xx series of TTL chips starting in 1964, and when I read TTL, I
expected to see 74xx chips.  The 74181 was introduced in February
1970, and I expected it to be in the HP-PA CPU, as well as in the VAX
11/780.  <https://en.wikipedia.org/wiki/74181> confirms my expectation
for the VAX, and the photo confirms my expectation for the first HP-PA
CPU.

The AS family was only introduced in 1980, so there was some advances
between the VAX and this HP-PA CPU indeed.  However, as far as the
number of boards is concerned, a 74AS181 takes as much space as a
plain 74181, so that difference is irrelevant for that aspect.

I leave it to you to point out a chip on the HP-PA CPU that did not
have a same-sized variant avalable in, say, 1975.

- anton
--
'Anyone trying for "industrial quality" ISA should avoid undefined behavior.'
  Mitch Alsup, <c17fcd89-f024-40e7-a594-88a85ac10d20o@googlegroups.com>