TD Systems TDL-11 QBUS (SCSI?) card

Sean Caron scaron at
Mon May 4 09:37:33 CDT 2015

Sorry, ambiguous, nothing wrong with the Z8400 or the Z80 in general; fine
architecture; I was just contrasting the more "ambiguous" design of a card
like that which is under discussion, to something that's just got an NCR
5380 or similar on it, that just jumps out at you and yells "SCSI!"



On Mon, May 4, 2015 at 12:41 AM, Eric Smith <spacewar at> wrote:

> On Sun, May 3, 2015 at 10:08 AM, Sean Caron <scaron at> wrote:
> > That this one turned out to be SCSI with the strange Z8400 CPU
> What's strange about a Z8400? That's a normal Z80 CPU. If there are
> two additional digits after "8400", that's the rated speed in MHz, as
> opposed to the older alpha scheme (Z80 = 2.5 MHz, Z80A = 4 MHz, Z80B =
> 6 MHz, Z80H = 8 MHz).

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