Dave, Very Interesting. I like the use of the serial use of the'181s. I wonder if they used data selectors for the in and outs or fed them with shift registers. I'll add that to my mental musings of how I would build a hardware emulation of the UNIVAC 1219. Too easy now to do it in software. On 1/28/2023 1:20 AM, Douglas Crawford via vcf-midatlantic wrote:
On 1/27/2023 9:49 PM, Dave McGuire via vcf-midatlantic wrote:
On 1/27/23 21:20, Douglas Crawford via vcf-midatlantic wrote:
One working circuit idea: I just was researching the TI ALU that some mini computers used prior to microprocesses, 74S181. It was pretty influential. The logic diagram could work as a graphic to wear: https://www.researchgate.net/figure/The-logic-diagram-of-the-74LS181-ALU-IC_...
74181, a great chip. There's a column of four of them in most of the earlier PDP-11 processors. The earlier DG Nova processors use a single one, making four passes through it for 16 bits.
Ken Shirriff did a very nice blog post about the venerable '181. It's worth a read.
-Dave
K.S. '181 Blog: https://www.righto.com/2017/03/
-- DuaneCraps sdɐɹɔ ǝuɐnp