Here my solution about CPU first generation of pinball Zaccaria. There are some improvements compared to the original.
I started to re-design from 1B1110/0-1, but I also included the possibility (by jumper) to switch from 1B1110/0 to 1B1110/1a (Locomotion).
Here the main improvements on revision 1.1:
- Switch old EPROM 2708/2716 with 2764 or 27512, like my Eprom adapter
- It’s possible use AS6C6264 RAM instead old 2101/5101 (U7-U8),
- PIC18 can generate CLOCK rather than U19 with RC filter (under test/not implemented yet)
- PIC18 can generate INTREQ, Watch DOG and drive RUN line (under test/not implemented yet)
- PIC18 can simulate RAM (instead of U7-U8) (under test/not implemented yet)
- Mosfet array instead of CA3081. No base resistors and the output it’s protected from false contact up to 50V
- 10k Pull-Up on databus for improve stability
- Added some bypass capacitors
- It is possible to use a backup battery (like CR2032) or the classic Ni-Cd with or without recharge.
The schematic can contect some errors, so if you try yourself do it, I don’t take responsibility for any damage to your pinball machines
Need some question? Want try this solution but don’t have the correct instruments?
Contact me, it will be a pleasure to help you.