The 4K Crisis in the 70's

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nsaspook

Joined Aug 27, 2009
16,251
One of my 8080AD (date code of 1976, 29 week on the 8080 chip) processing computers from that era that used the 2114 SRAM chip. The only Intel chip was the D8228 System Controller and Bus Driver.
I should have invested in old gold-white 8080AD chips as they are listed for insane prices online. https://picclick.com/Vintage-National-Semiconductor-8080-CPU-INS8080AD-Gold-White-124177524490.html
https://en.wikichip.org/wiki/File:MCS-80_Users_Manual_(Oct_1977).pdf
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Lower row. Memory board with 2114 main SRAM memory and a 2716 UV erasable ROM for the main program memory. Of course it all used 8080 assembly language.
Upper Row. Debugging panel and GPIO board using the classic Intel 8212 8-bit I/O port chip (this board used 8212 chips from NEC and National).
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One set of 2114 chips were piggy-backed to get a extra 1K of SRAM memory with the wire select wire on the pin.

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Here the decode address from the SN7442 BCD to 10 line decoder (pin 5 for bank 4 of banks [0..4])wire-wrap pin goes into a hole for each 2114 chip select of the 2 chip SRAM bank.
 
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sagor

Joined Mar 10, 2019
1,046
Ah, brings back lots of memories. I remember wire wrapping on similar boards (simple projects). I still have a collection of older EPROMS (2708/2716 and even an 8702). I guess I should hang on to my 2141 rams chips for nostalgia, not to mention the good old 8085/Z80 chips...
I used a lot of 2716 chips in the old days when one still wrote BIOS routines for CP/M
 
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