On 2009-05-01, Michael A. Terrell wrote:

"DoN. Nichols" wrote:

Actually -- no. Among other things, I never had an Intel 8080
based system (nor a Zilog Z80 based system), nor one which ran CP/M.
After my homebrew minimal OS built around a digital cassette tape drive,
I moved on to the SWTP 6800 and 6809 with SSB's (Smoke Signal
Broadcasting's) DOS-68 and DOS-69, and then on to OS-9 for the 6809
system.


I have most of two SWTP 6800 systems in the garage, if they weren't
damaged aby a leak a few years ago. Somone added a pair of 5.25" floppy
drives to one of them.

Hmm ... I wonder which of the floppy controller boards that was?
SSB (Smoke Signal Broadcasting) was one of the makers, and they had a
neat trick to save address space. The I/O ports were eight groups of 32
addresses separated by 32 blank address spaces.

The SSB ROM was wired and programmed to fill all of those 32
byte gaps, so it did not take away anything from what the rest of the
system was using. Tricky programming -- and it *had* to be assembly
language programming to allow that much control of the address spaces.

TSC was another maker of floppy controllers in the early years.

IIRC, both started with two 5-1/4" floppies. Later ones would
handle double density and double sided, and the final ones would also
mix 8" with 5-1/4" ones.

Gimix made the best of them in the later days. 4 8" and 4
5-1/4" drives on a single controller.

The SSB ones usually had an Indian head in warbonnet as a logo
on the board. I don't know what the TSC ones looked like, because I
used SSB exclusively.

Enjoy,
DoN.

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