On October 29, you wrote:
> > [The 11/730] was the slowest VAX ever shipped, with the only possible
> > exception being the MicroVAX-I.
> 
> The 725 was faster?  I always thought the 725 was a stripped-down (and
> slower) version of the 730.  (I remember decommissioning a 730, or
> maybe a 725, I forget...we were trying to find the CPU and eventually
> decided, only half in jest, that t'was a Z-80 running a VAX emulator.)

  The 725 and the 730 use the same CPU.  The differences are primarily
physical chassis things.

  If you were looking on the 725's boards for a chip that you'd call a
"CPU", well, the CPU in those machines is two whole boards (three?) of
chips.  Look for a large field of AMD 2901 bit-slice microprocessors
(40-pin DIPs) and that's basically the ALU and condition-code stuff.
Somewhere nearby you might find a 2910 (popular for use with the 2901
but I don't remember if DEC used one in the 725/730) microsequencer,
which basically handles microcode-level program counters and jump
processing.

  It really is a neat design...slow as pissing tar, but a neat
design.  If Ragge (or someone) gets NetBSD/vax running on one, I'll go
find one and run it...that's for sure! :-)


                         -Dave McGuire
                          mcguire@neurotica.com