TRS-80 Fragmentation

Carlos E Murillo-Sanchez ce.murillosanchez at
Thu Apr 26 22:23:27 CDT 2018

Eric Smith via cctalk wrote:
> On Thu, Apr 26, 2018, 15:59 Bill Gunshannon via cctalk <
> cctalk at> wrote:
>> I believe the Z-80 was subordinate to the M68K.
> In high-level conceptual term, maybe, depending on the software.
> In term of the actual capabilities of the hardware, the Z80 was firmly in
> control of _everything_ in the machine, including control over the MC68000,
> while the MC68000 had no direct control over anything but its MMU (built
> from TTL) and memory. If code running on the MC68000 wants to talk to
> anything at all, disk, tape, console, printer, serial ports, etc., all it
> can do is politely request that of the Z80. In that sense it's like the CPU
> of a CDC 6600, which can't do anything without the PPUs
Interesting.  HP made ISA card versions of early (or actually, pre-)  
HP9000-300 that were designated as "Basic Language Processors", hosting 
a 68000 and having GPIB I/O.  Interesting beasts. I believe that they 
were able to take control of the ISA bus for at least some functions; 
they were fast for their time, and it was easy to share GPIB-acquired 
data with the MSDOS world.

More information about the cctalk mailing list