Simulated CP/M-68K?

On 6/15/07, Al Kossow <aek at bitsavers.org> wrote: OK. I was hoping it was that simple. I have a number of 68K-based boards, nearly all have serial ports, some have mass storage, some could have it added. In particular, I have a stack of COMBOARDs with between 128K-2MB of RAM, and either a COM5025 (sync only, but could be easily replaced in-socket), or a Z8530, but the closest thing to mass-storage would be a 6821 on the Unibus and Qbus models that could be pressed into service as a CF interface via an IDE adapter (8-bit mode would be easy; 16-bit mode might require some additional logic). Much like my long-standing dream of putting CP/M on my "Z-80 starter board" (that has one or two S-100 sockets on it already), I think it would be fun to take one of these COMBOARDs and make a general purpose computer out of it (since I own the rights, I already have the schematics). If I took the most common one I have on hand, the COMBOARD-II, it has a 8MHz 68000, 128K of parity DRAM, a pair of 2764 EPROMs (16-bits wide), a 6821, a COM5025, and an essentially useless-for-this-application Unibus DMA interface. Presuming that CP/M-68K doesn't have an issue with the differences of a 68010, one could drop one in there, too. I think I'd probably fit some other UART into the COM5025 socket, then either rig up a swabber cable to repin the LP05-style on-board printer port to something that resembles an IDE port, or to bypass the 6821 entirely and just borrow its attachment to the chip select, low address bits and data bus of the 6821 and route _that_ to an IDE-to-CF adapter. There not being a massive demand for CP/M-68K machines, this would all be for fun, and probably not as easy as starting off with a simple purpose-built 68K SBC, but I think it would be entertaining to take a VAX peripheral and turn it into a full-blown computer. I suppose one could do something similar with a DMF-32 (which is also 68000-based), and you'd even have 7 spare serial ports. Much to mull over. If anyone _does_ come up with a UNIX-based virtual environment for CP/M-68K, I'd love to hear about it - I might as well give things a stab in a virtual sense before breaking out the soldering iron. -ethan