🚀 go-pugleaf

Hi all,
    Just an update on the QIC tape backup program.  I've temporarily
placed the whole project on hold because I'm going through final exams
and will be spending the first two weeks of January in Europe (it's a three
credit class and I needed to taks it so I can graduate on time).  (NO! REALLY!
I honestly NEED to travel to Paris and London.  For School!  REALLY!)
    I received a rather complete set of documentation from the QIC standards
committee, all for free.  The documentation does not include the Colorado
Memory System's parallel interface for tape drives, but it has the full specs
on something even better.
    It turns out that the QIC-80 and QIC-40 standards, which all internal
1/4" tape drives use, use an MFM type of interface that is compatible with
the standard floppy drive interface.  The Bottom Line:  IF ALL GOES WELL
YOU WILL BE ABLE TO PLUG ANY 1/4" TAPE DRIVE INTO THE SAME CABLE YOUR
FLOPPY DISKS ARE ON NOW.
    Now the tape drive does not talk to the floppy controller in exactly the
same way as a floppy drive, of course.  There are a whole set of commands
(38 to be exact) which can be sent to the tape drive by "stepping" the STEP
line on the 34-pin cable.  This makes sense since the STEP line is not normally
used for the tape, and the floppy controller will generate STEPs in a "fire and
forget" mode.  The tape drive sends its response (now get this) on the "TRACK
ZERO" wire of the interface.  This can be read out on the status register of
the 1797.
    The commands are sort of a modified bit-bang; each bit comes from the
floppy only AFTER the controller requests it (so you don't have to block
all interrupts or HALT the CPU or anything).  The actual reading and writing
uses MFM just like a floppy, but the formatting information and CRC stuff
is all different.  There are also specs for error correction and data
compression which I will implement in the driver after I get the basic driver
running.
    So to summarize: I have the information I need and the hardware I need
for the CoCo version.  I'm going to concentrate on the floppy interface since
EVERYBODY has a floppy controller, wheras not everyone has a parallel port.
Once the CoCo version is up I can support someone writing an OSK version, and
add data compression and error correction.
    And maybe, just because they p*ssed me off, I'll figure out how the parallel
port interface works and publish a driver in public domain.  Maybe.
Holiday Cheer!

   -Rich