28 Feb
2005
28 Feb
'05
1:21 p.m.
So I made the adapter cable to connect an 8" drive to my PC. The basic
connections seem to be there. I can actually format a disk from MS-DOS,
at least halfway, meaning the drive goes through the motions of formatting
all 77 tracks but then when it goes to write the directory and other
whatnot it can't move the head back to track 0. The format aborts saying
it can't write the boot sector.
If I then try to DIR the disk the head backs up a track or so but can't
seem to recalibrate to track 0. The head vibrates as if the drive is
sending the signals to the stepper to retract the head but it only manages
to move back a track or so each time I issue DIR. If I do it enough it
eventually gets back to the stop position but it still gets sector errors.
I verified that the drive susbsystem I'm using is good by booting RT-11
off it. I was able to access both drives in the system from RT-11. The
PC system only sees drive B:, or at least when I try to access drive A:
(which is configured in the BIOS as a 1.2M 5.25" floppy, as is drive B:)
it does not engage the head. The notes I used to make my cable indicate
that this might be what I should expect, since it said to jumper the 8"
drive as Drive 1:
http://home.iae.nl/users/pb0aia/cm/8-525.html
"Set the drive to respond to Drive Select 1 (the default for PC drives)"
(under the "Drive links" section).
So I suppose it would make sense that the PC only sees drive B (drive
select 1). Or does it?
Any ideas?
--
Sellam Ismail Vintage Computer Festival
------------------------------------------------------------------------------
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28 Feb
28 Feb
6 p.m.
On Mon, 28 Feb 2005, Vintage Computer Festival wrote:
If I then try to DIR the disk the head backs up a
track or so but can't
seem to recalibrate to track 0. The head vibrates as if the drive is
sending the signals to the stepper to retract the head but it only manages
to move back a track or so each time I issue DIR. If I do it enough it
eventually gets back to the stop position but it still gets sector errors.
Wrong step rate! Poke a new on eint othe chip, or does it use the old
table of junk INT 13h used to supoprt?
1 Mar
1 Mar
11:10 a.m.
On Mon, 28 Feb 2005, Tom Jennings wrote:
On Mon, 28 Feb 2005, Vintage Computer Festival wrote:
Um, I'm not sure. I'm not sure I understand the question either. This is
a standard ISA IDE+floppy controller. Should I try an older one? Or hook
this up to an oldr PC from the 1980s?
--
Sellam Ismail Vintage Computer Festival
------------------------------------------------------------------------------
International Man of Intrigue and Danger http://www.vintage.org
[ Old computing resources for business || Buy/Sell/Trade Vintage Computers ]
[ and academia at www.VintageTech.com || at http://marketplace.vintage.org ]
If I then try to DIR the disk the head backs up a
track or so but can't
seem to recalibrate to track 0. The head vibrates as if the drive is
sending the signals to the stepper to retract the head but it only manages
to move back a track or so each time I issue DIR. If I do it enough it
eventually gets back to the stop position but it still gets sector errors.
Wrong step rate! Poke a new on eint othe chip, or does it use the old
table of junk INT 13h used to supoprt?
3:01 p.m.
On Tue, 1 Mar 2005, Vintage Computer Festival wrote:
Different floppy drives have different specs for the stepper motor
step rate. Big drives are often slower (eg. 8" but that's not
always true). With 5.25's you never think about it, but it used
to be a Big Deal.
If you step it too fast it shudders and goes nowhere. There's an optimum
rate for performance, but "too slow" would be just fine for sucking data
off diskettes one time.
It's programmable on a 765. If you run an unprotected OS like DOS
you could write a tiny program in DEBUG, save it, and run it when you
need to talk to the big floppy.
ALl those bits left my brain, you'll ahve to RTFM or talk to
someone who still has them in core.
Wrong step
rate! Poke a new on eint othe chip, or does it use the old
table of junk INT 13h used to supoprt?
Um, I'm not sure. I'm not sure I understand the question either. This is
a standard ISA IDE+floppy controller. Should I try an older one? Or hook
this up to an oldr PC from the 1980s?
3:18 p.m.
On Tue, 1 Mar 2005, Tom Jennings wrote:
On Tue, 1 Mar 2005, Vintage Computer Festival wrote:
Different floppy drives have different specs for the stepper motor
step rate. Big drives are often slower (eg. 8" but that's not
always true). With 5.25's you never think about it, but it used
to be a Big Deal.
If you step it too fast it shudders and goes nowhere. There's an optimum
rate for performance, but "too slow" would be just fine for sucking data
off diskettes one time.
So what I'm wondering is why it works fine when it's stepping towards the
center of the disk but not when it's stepping back out.
As I mentioned previously, the format command actually works: it steps 77
tracks inward, but can't move back to track 0 to write the boot sector and
directory.
--
Sellam Ismail Vintage Computer Festival
------------------------------------------------------------------------------
International Man of Intrigue and Danger http://www.vintage.org
[ Old computing resources for business || Buy/Sell/Trade Vintage Computers ]
[ and academia at www.VintageTech.com || at http://marketplace.vintage.org ]
Wrong
step rate! Poke a new on eint othe chip, or does it use the old
table of junk INT 13h used to supoprt?
Um, I'm not sure. I'm not sure I understand the question either. This is
a standard ISA IDE+floppy controller. Should I try an older one? Or hook
this up to an oldr PC from the 1980s?
3:42 p.m.
On Tue, 1 Mar 2005, Vintage Computer Festival wrote:
So what I'm wondering is why it works fine when
it's stepping towards the
center of the disk but not when it's stepping back out.
It's called "being on the hairy edge". Try refrigerating, or
heating, the drive. Put a drop of alcohol on the lead screw right
before you seek. Try it at night, or morning.
3:42 p.m.
when you are formatting tracks you have effectively slowed the stepping
rate down to a rate slow enough for the stepper motor to keep up with
(step, time to format, and then step again...). When you are returning to
track 00, the drive is stepping at the fastest rate that the controller is
configured for.
best regards, Steve
At 06:18 PM 03/01/2005, you wrote:
So what I'm wondering is why it works fine when
it's stepping towards the
center of the disk but not when it's stepping back out.
As I mentioned previously, the format command actually works: it steps 77
tracks inward, but can't move back to track 0 to write the boot sector and
directory.
--
Sellam Ismail Vintage Computer Festival
7236
days inactive
7237
days old
6 comments
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