Error correction in dynamic RAM designs. (1981-1982)
This technic gave the ability to use bad chips or to correct the famous problem due to alpha particules
found in ceramic packages. Ceramics were not enough pure and contained active nuclear components
giving alpha particules, adestroying some precious bits in memories...
To have 64 KB of memory, it was necessary to wrap 128 chips. It was a very hard job! (4096 wires)
I used at this time some kind of skycrapper. It was necessary to be able to change a chip to repair memory.
So I used chip holders. (It was not so simple!)
Here you can see 2 kinds of memories (1979-1980)
One with 2114 chips and another one with 6514 (to have data retention when powered off)
Chips are 1kx4 (cmos for 6514)
Before chips were soldered each upon others, ... but to repair, no solution!