Self modifying code, lambda calculus - Re: ENIAC programming

tony duell ard at
Sat Sep 19 00:15:06 CDT 2015

> Simple answer. The control store functionality had to fit in the available space
> on one hex
> sized card, and 16K density DRAM was the only option. Allocating additional
> space to use
> 4K or 1K SRAM would have pushed the CPU design to an additional board, which was not
> a design option at the time.

The 11/730 was released in 1982 (according to Wikipedia which I don't take a gospel, but
I have no other source of information for this). The PERQ 1a was certainly out by then, it had
a control store using 16K*1 SRAM chips. OK 20 pin as against 16 pin packages, but I don't
think the 11/730 boards are that tighly packed (anyway, using SRAM would probably have
eliminated some support devices like address multiplexers).


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