I've (almost) finished assembling my Apple-1 NewtonByte Prototype. So far it passed the smoke test, but I ran into an issue when the 7400 (B1) is inserted; it's displaying 4 vertical columns with random garbage even after pressing clrscr/reset. With the 7400 (B1) removed, the screen is filled with flashing "@_" as expected, and after resetting, I get a "@" prompt in the top-left corner but that's it. I am guessing it's related to having the 6800-only being populated.
Note: I followed the instruction provided by MichaelNG with the purchase of his board incl. cutting and jumping the recommened traces. I also ensured that I connected the +5V to the correct A4-6820-24 pin (photo in the intructions is wrong).
Question: Did anyone run into similar issues while building a functioning Apple-1 A Prototype? If so, what components did you used to poplate the 6800-only area to get it working and did you have to make any additional changes to the 6800-only area. (I see one more cut which is not documented).
It might be wrong, but here's what I've tried with so far in the 6800-only. It's all I had laying around and appears to match the labels on my other A1 boards
- 4x 22 uf Allen Bradley carbon resistors
- 4x MPS3704 NPN TO-92 transistors
- 2x 104 1.0 box capacitors
- 4x 1K uf Allen Bradley carbon resistors
- 4x 103 0.01 disc capacitors
I've successfully built two fully functioning Apple-1 (a Non-NTI and a NTI) without issues. But, the Prototype PCB is a bit different and has the 6800-only area populatd while running the 6502 CPU.
It's worth noting that I've tested the 7400 in one of my other working Apple-1's and it's fine.