This project is obsolete. For a new hardware project, combining the 8088 card, memory expansion and other hardware features, see the repository at:
https://github.com/MichalPleban/cbm2-8088-ram-board
This is the replica of the 8088 processor card for the Commodore CBM-II computers, made by Ruud Baltissen. The replica is 100% compatible with the original card.
The following changes have been made to the replica:
- JP3 was added to allow installing the 8087 co-processor. This jumper is missing from the original card.
- Card EPROM has been enlarged to fill the whole F000 segment.
- The very hard to obtain 6525 chip has been replaced by a standard 8255 I/O chip.
You can use the original MS-DOS 1.25 and CP/M-86 1.1 software with the card. However, the ROM also contains the 0.66 version of PC compatibility layer, allowing it to boot newer versions of PC-DOS and MS-DOS.
The enlarged EPROM contains boot files of PC-DOS 3.2. To boot this system, create a disk from the attached empty.d80 orempty.d82 image, and press Shift+RunStop to bootstrap the disk. The disk will load the 6509 part of the IPC library into memory and boot PC-DOS from the EPROM.
The card has been successfully tested with a high-profile CBM-II machine, using either 8088 or V20 processor, as well as 8087 co-processor.