VAX 730 was Re: Self modifying code, lambda calculus - Re: ENIAC programming

tony duell ard at
Sat Sep 19 05:53:36 CDT 2015

> The biggest risk I remember from the 730 design (I worked in the same hardware
> lab, different project: 11/74 CIS) was the extensive use of PALs. This was the
> first (I believe) project at DEC to use them, and they were basically buying all

It may well have been. Certainly the 11/730 is full of PALs, this is how (I think) they got
a complete VAX CPU onto 3 hex boards using standard ICs. The only custom parts (as
opposed to custom programmed parts) in there are the 2 gate arrays for the memory
ECC which are the same as the ones in an 11/750.

DEC were also using the 82S100 PLA at around that time. Whether it was first used 
before the 11/730 I don't know (I suspect it was). 

Don't get me wrong, I like the 11/730, and apart from the use of DRAM for the 
control store I think it is a very interesting and neat design. It is one of only 2
VAX families I would consider trying to run, and due to space constraints it's the 
only one I can run (the other being the 11/780, and no way do I have room for one
of those).


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