1 Jan
2011
1 Jan
'11
9:15 p.m.
On 1 Jan 2011 at 18:24, Tony Duell wrote:
You might manage to fiddle with the positioner control circuity of an
Epson SD320 series drive too. That's the voice-coil one with an optical
feedabck syustem somewhat similar to the RK05.
I then thought that if the offset was close to an
odd multiple of half
the track spacing, then perhaps you could use a drive with twice as
many cylinders nad read the odd rather than even tracks (e.g. use an
80 cylinder 5.25" drive to read a40 cylinder flippy). Alas, that
doesn't work either. IIRC, the side 1 head is offset towards the
spindle, so you can't move the head out far enouth to read the
otuermost sylinders on side 1 of a flippy.
Since we're talking about 5.25" "flippies" (although 8" flippies
existed and were sold by established manufacturers), a Drivetec drive
might do the trick, if one wanted to rework the microcontroller
firmware. Since the Drivetec is essentially a closed-loop servo
system with two motors for positioning (one coarse, the other fine),
it might be possible to hit the opposite-side tracks correctly.
Of course, there aren't many Drivetec drives out in the wild as they
were never very popular.
Howevr, if the side 1 head is offset towards the speindle (as I think it
is), you'd have to step the caarriage out beyond the noraml cylinder 0
position to get the side 1 head over cylinder 0 on the flippy. And that,
I suspect, would mean modifications ot the drive.
I also don't know if "half-stepping" the positioner on a conventional
drive would work either, as it would take a rework of the drive
electronics.
I was thinking that if the offset was close to a multiple of half the
normal track spacing (and I think it is). you might be able to use, say,
an 80 cylinder drive to read a 40 cylinder flippy. Noramlly the 40
cylinder positions align with the even-numbered 80 cylinder positons. So
half a cylinder offset would mean they corresonded to the odd-numbered 80
cylinder positions. So you probably could read some of the cylinders
that way
But it doesn't help with the fact that uoui'd have to move the carriage
out beoyond the cylidner 0 postion.
-tony