The Eurocom6502
What is it?
The design is based on Eltec's Eurocom-I or better, my remake of it.This version is equipped with the MOS 6502, well known for its use in various Commodore, Aplle and Atari computers. Converting the schematic and board to this new 6502 version took less than half an hour.
The schematic
The board
The Eurocom6502B
Same as the above board but now the 6821s have been replaced with 6522s.I kept the 6850, I did not replace it with the 6551. Reasons: I never worked with the 6551 and heard/read that the 6850 is better. Same as the above board but now the 6821s have been replaced with 6522s.
I kept the 6850, I did not replace it with the 6551. Reasons: I never worked with the 6551 and heard/read that the 6850 is better. Remark: I completely forgot about the fact that the 6522 has on board timers and so the timer made out the 74LS393 is in fact not needed. If not used, just don't install the parts.
The schematic
The board
The Eurocom6502C
Version C has been created after creating version C of the Eurocom80552. Main idea: drop the two original Eurocom DIN connectors and move the Elektor connector from the left side to the top-left. I didn't want to drop the second 6522 so I replaced the DIN connector with a 26-pin header, configered like the printer/LPT port of a PC. Not wanting to waist three left over I/O pins of the 6522, I put them in the place of three of the eight original Ground pins of this connector.I also added the output of CB1 of the first 6522, CB12, to the GAL to be used as a memory switch: it enables the user to replace the ROM with RAM.
The schematic:
The board:
You can email me here.