22 Aug
2018
22 Aug
'18
2:11 p.m.
On Wed, 22 Aug 2018, Eric Smith via cctalk wrote:
Unfortunately I don't recall the model number, but
there was a Shugart 5
1/4" drive that made it at least to prototype and field test around late
1980 or early 1981. It was supposed to be really inexpensive, but almost
plug-compatible with standard drives like the SA400. Unlike the SA390, it
did have electronics.
Instead of being built on an aluminum casting, it only had bent metal. The
head stepping mechanism worked like an 8-track tape. It used a solenoid to
advance one track inward; the only way to go outward was the next step from
the innermost track returned to the outermost (track 0). The single track
step time was incredibly slow; I think it was around 750ms, vs 40ms for an
SA400.
My employer at the time, Apparat, then famous for NewDOS-80 for the TRS-80,
had one for evaluation, but decided not to resell them. It would have
required special software support, which Apparat could have put in
NewDOS-80. Presumably patches could have been offered for other TRS-80
operating systems.
I wasn't told what the retail price of the drive would have been, but I
don't think it would have sold well even at 1/4 the price of an SA400.
Neat!
That could have given Exatron Stringy Floppy a run for the money!
Both in terms of CHEAP ("race to the bottom"), low-speed, and probably
reliability.
Are you sure that that was 750ms track to track step, not 75ms?
There were a few 128K machines then. Easiest patches to get around the
ridiculously slow speed (going from track 17 (TRS-DOS directory) to track
16 would require 750ms per track to 34 or 39, recalibrate (seek to 0,
probably LESS than 750ms) and step 750ms per track from 0 to 16) would
have been to cache a dozen tracks, particularly directory, in RAM.
'Course those opting for 128K would also spend the premium for a
half-decent drive, . . .
It would also argue for the track 0 directory (PC-DOS, Mac, etc.) V the
"seek center" track 17 of TRS-DOS, etc.
I wonder why Radio Shack didn't consider THAT for the CoCo? They did
everything else they could to sabotage it into being a home kids machine
and avoid it being usable for anything further. (chiclets keyboard, RF
without composite video, 32 characters per line, . . . some of which
could be fixed)
You will recall that the use of the QumeTrak 142 drive in "PortablePC"
(5155) and PCJr required a change in PC-DOS 2.00 to 2.10 for slower step time.
--
Grumpy Ol' Fred cisin at xenosoft.com