Somewhere I picked up a pair of these Multibus I cpu boards. They have a Motorola 68010 processor (running at 10 Mhz) along with 1M of RAM, dual serial ports via the Zilog Z8530 SCC, and a number of other support chips (including an optional 68450 DMA controller).

I am running them in an old Intel PSBC 660 8 slot chassis. The power switch in this chassis is flakey, so I use the power cord to turn things on and off once I get the switch to turn on. It says a lot for Intel's high quality standards that this thing is still running after 30 years. There is something odd about this chassis though, the CPU boards will not run in slots 7 or 8.

My board "A" has a 68010/10, no DMAC, and runs my blink roms OK. While running only the S light is on of HBDUS. I pulled the 68450 DMAC from board B and put it on this board (for safe keeping while I try to repair board B), and board A is still running fine.

My board "B" is marked "Production Test", has a Hitachi 68000/10 along with a Hitachi 68450 DMAC. This board does not run my blink ROMs. This Hitachi CPU is OK (it runs on board A). I tested it with the DMAC pulled, and it still doesn't run. While halted only the H light is on of HBDUS.

Note that the manual says that the DMAC can be pulled if it is not wanted or needed.

My test ROMS

I wrote a second version to avoid touching RAM, hoping that board B was not running due to a memory issue, but this did no good. I did run this at address FC0008, maybe I should just run it at address 0x8 and avoid any hint of enabling RAM. Actually I think I will need some scope loops, if I can get anything to run at all. Maybe a rom that has a reset vector to address 8 and put a single instruction that branches to 8 at address 8. That is about the simplest thing I can think of.