HiI received a non-working Disk II Interface Card - I assume, the disk's ribbon cable was connected incorrectly… I compared the card to a working one by measuring the expected signals and swapping chips. A total of 3 ICs failed --> C3 (74LS323), B2 (74LS05) and B3 (PROM P6).
The two TTL logic IC's were easily replaced with spare parts I found. The real problem lies in P6. By replacing it with another P6 from a working card, I verified, that the interface card is working. Some research led me to the AMD AM27S23APC PROM, which is avaylable on E-Bay. But… I don't have a programmer to write the Code into the PROM.
So I'm looking for:
- a) a spare P6 (16 Sector Programmed)
- b) an alternative for the AM27S23APC - which could preferably be programmed with the TL866II plus
- c) a way to programm the AM27S23APC
Any answer to any of these 3 questions would be extremly helpful.