5 Nov
2007
5 Nov
'07
11:04 p.m.
I want to use a QUME 842 or SA800 in an altair disk subsystem.
Both seem to have the same interface.
The FD400-5x0-5x1 manual seems to show the drives being quite similar.
The first thing I see is that there are extra signals.
"Trim Erase", "Write Enable", and "Write Data" where the
Shugart
interface only has "Write Data" and "Write Gate". I assume that gate
and enable are the same thing. The FD Pertec drives also have "IN",
"OUT", and "STEP" instead of "STEP" and
"DIRECTION", but that is not
a big deal. That can be generated in software.
What I don't see is any input to perform the function of head
current. How does the shugart interface handle this?
Can I ignore the trim erase feature? How do I generate a write busy
signal? I'm willing to make some circuits to fake these signals if required.
Thanks,
Grant
5 Nov
5 Nov
11:50 p.m.
New subject: 8" disk drive project - maybe 3.5" project too???
I'm going to add some to my own topic. The questions below still
stand, but I've got more info! : )
I want to use a QUME 842 or SA800 in an altair disk
subsystem.
Both seem to have the same interface.
The FD400-5x0-5x1 manual seems to show the drives being quite similar.
The first thing I see is that there are extra signals.
"Trim Erase", "Write Enable", and "Write Data" where the
Shugart
interface only has "Write Data" and "Write Gate". I assume that
gate and enable are the same thing. The FD Pertec drives also have
"IN", "OUT", and "STEP" instead of "STEP" and
"DIRECTION", but that
is not a big deal. That can be generated in software.
What I don't see is any input to perform the function of head
current. How does the shugart interface handle this?
Can I ignore the trim erase feature? How do I generate a write busy
signal? I'm willing to make some circuits to fake these signals if required.
More info:
The pinout of an Altair disk drive...of the wires connected. Omitted
pins are either not connected, power, or ground. All lettered
connections are ground.
6 - Output - Door Open (IDOP
7 - Head Current Switch (IHCS)
8 - External Trim Erase (Option) (IEEN)
9 - Input - Write Enable (IWEN)
10 - Input - Write Data Input (IWDA)
11 - Input - Step In (ISTI)
15 - Input - Step Out (ISTO)
16 - Input - Head Load (IHLD)
17 - Output - Index (IINXP)
18 - Input - Drive Motor On (IDEN)
19 - Track 0 (ITRK0)
20 - Output - Read Data Output (IRDA)
One thing that interests me slightly more is the possibility of a
regular 3.5" disk connected to the Altair. I don't care about the
encoding or format being compatible with a standard controller.
It is very similar, but is also a soft sector disk/drive. How close
is close? Can I just use a microcontroller with a timer to time from
one index to the next and divide it up into 32 sectors? Will this be
close enough for the Altair? Anyone know what kinds of errors I
would get? A microcontroller running at 16MHz would be able to count
between pulses with 16MHz/1 accuracy. With the SA800 I would have a
sector hole sensor giving me the correct timing.
There still is the issue of the write trim erase feature, whatever that is...
Any comments or ideas on the idea? Is it worth trying? I've got a
very weird tarbell card that formats and uses 3.5" disks as a 70k
mini floppy. I guess anything is possible. : )
2 - Density Select (/REDWC)
8 - Index (/INDEX)
10 - Motor Enable Drive 0 (/MOTEA)
12 - Drive Select 1 (/DRVSA)
14 - Drive Select 0 (/DRVSB)
16 - Motor Enable Drive 1 (/MOTEB)
18 - Direction Select (/DIR)
20 - Head Step (/STEP)
22 - Write Data (/WDATE)
24 - Floppy Write Enable (/WGATE)
26 - Track 00 (/TRK0)
28 - Write Protect (/WPT)
30 - Read Data (/RDATA)
32 - Head Select (/SIDE1)
34 - Disk Change/Ready (/DISKCHG)
I'm not going to sleep a wink tonight. I hate having ideas at 10PM... : (
Grant
6 Nov
6 Nov
12:13 p.m.
New subject: 8" disk drive project - maybe 3.5" project too???
On 5 Nov 2007 at 22:50, Grant Stockly wrote:
I happen to have a copy of the manual for Don Tarbell's first floppy
controller for S-100 machines. While not particularly interesting
from the controller standpoint, there is a fair amount
of "I've got
this drive; how can I make it work with your
controller?"
information.
And--ta-da--one of the drives mentioned is the Pertec FD400. What
follows is what one would need to do to connect an Altair drive to a
Tarbell controller that's been hooked to the 37-pin Altair case
connector. So the pin numbering given here is of the 37-pin
connector, not the Pertec drive connector. My commentary is added.
Understand that this is sort of "inside out", but should give you a
good idea of what's what--and the Tarbell controller is documented to
a fare-thee-well.
Here's what Don's got (again, note that the pins are the DC-37 pin
numbers).
Pin 5 - Write Data; same as 842 WD
Pin 4,3 Write gate and Trim Erase; tie together and interpret as WG
Pin 2, Current select; same as 842 TG43/RWC
Pin 9, Index; same as 842 INDEX
Pin 1, Ready; same as 842 READY
Pin 13, Enable; tie to GND so drive is always enabled
Pins 6 and 7, Step In and Step Out. You'll need a little glue to
generate STEP and DIRECTION pulses from these. You may want to add a
little delay to make sure that DIRECTION is asserted slightly before
STEP--check the 842 docs on this one.
Pins 15 and 14, Drive Select 0 and 1; same as 842 DS0 and DS1
Pin 8, Head Load, same as 842 HLD
Pins 16 and 17, DA-C and DA-D; tied to ground
Pin 18, NEXT DE - tied to ground
Pin 10, Track Zero - Same as TK00 on 842
Pin 11, Raw Data; same as RDATA on 842
I don't know if this is terribly helpful, but it's a starting point.
Cheers,
Chuck
One thing that interests me slightly more is the possibility of a
regular 3.5" disk connected to the Altair. I don't care about the
encoding or format being compatible with a standard controller.
It is very similar, but is also a soft sector disk/drive. How close
is close? Can I just use a microcontroller with a timer to time from
one index to the next and divide it up into 32 sectors? Will this be
close enough for the Altair? Anyone know what kinds of errors I
would get? A microcontroller running at 16MHz would be able to count
between pulses with 16MHz/1 accuracy. With the SA800 I would have a
sector hole sensor giving me the correct timing.
There still is the issue of the write trim erase feature, whatever that is...
Any comments or ideas on the idea? Is it worth trying? I've got a
very weird tarbell card that formats and uses 3.5" disks as a 70k
mini floppy. I guess anything is possible. : )
2 - Density Select (/REDWC)
8 - Index (/INDEX)
10 - Motor Enable Drive 0 (/MOTEA)
12 - Drive Select 1 (/DRVSA)
14 - Drive Select 0 (/DRVSB)
16 - Motor Enable Drive 1 (/MOTEB)
18 - Direction Select (/DIR)
20 - Head Step (/STEP)
22 - Write Data (/WDATE)
24 - Floppy Write Enable (/WGATE)
26 - Track 00 (/TRK0)
28 - Write Protect (/WPT)
30 - Read Data (/RDATA)
32 - Head Select (/SIDE1)
34 - Disk Change/Ready (/DISKCHG)
I'm not going to sleep a wink tonight. I hate having ideas at 10PM... : (
Grant
4:03 a.m.
Grant Stockly <grant at stockly.com> wrote:
What I don't see is any input to perform the
function of head
current. How does the shugart interface handle this?
This is usually called TK>43 or TG43 or something like that,
assuming you are talking about changing the head current as you step
to the inner tracks.
Tim.
6256
days inactive
6256
days old
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