ROM dumps of Intel MDS-2 IOC

Eric Smith spacewar at
Mon May 18 21:48:49 CDT 2015

On Mon, May 18, 2015 at 5:55 PM, Dave Mabry <dmabry at> wrote:
>> As have I.  I found that the IOC firmware has undocumented 0dh and 0eh
>> commands. Command 0x0d allows the main CPU to write to arbitrary IOC
>> memory,

> One of the enhancements in the iMDX-511 was a fast block write to the crt.
> I'd bet that write to arbitrary IOC memory has something to do with that.

No, that's command 0x0f which is documented, and can only write to
screen memory.

> I made two or three RPC86 boards from SBC-86/12 boards.  It wasn't very
> easy.

That was something I was hoping to do also, if I can't obtain an RPB
or RPC, but can obtain an 86/12A, 86/14, or 86/30.  It's encouraging
that you've confirmed that it's possible, but discouraging that it
sounds like a lot of work.

> I sent out your Single Density ISIS-II 4.3 boot diskette today with Kermit


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