As I showed in my previous topic, I am finishing building two Apple 1 replicas.https://www.applefritter.com/content/my-version-apple-1-replica
Everything works as it should. Most of the TTL chips are from my inventory.
While browsing the photos of the original Apple from 1976, I noticed that the C8 position is the 7451 and not the 7450 (as in the original schematic and PCB description). This interested me, and I know the differences between the 7450 and the 7451. I also know that the 7451 or 74S51 is not the same as the 74LS51 (2 or 3 NAND inputs).
BUT, does anyone know why there are these discrepancies between schematic / PCB and finished products?
BTW, 7450 were widely available in my country (UCY7450 from CEMI - Polish semiconductor manufacturer during the Cold War and Communism), but the 7451 were not available at the time.
In my resource I found 7451 ITT with datecode 7229 (CDIP) which I used in one of the replicas and it works fine.
Mateusz / SQ9PXB