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· Hardware
5.25" Drive==>AmigaDOS?
13 messages in this thread
I've tried to format my 5 1/4 disk for ammiga and failed in half way through
the verify cycle- exactly half way. I didn't try to write on this disk, so
maybe I do have 360K of useable 5 1/4 disk for my Amiga OS. I also found out
that when emulating PC my clock begins to lose time right away. Does anyone
know why?
The system time is based on the 'tic' interrupt. This time is based on the
60hz line frequency and is a low priority interrupt. Apparently, this
interrupt is held off when Transformer runs.
The system time is based on the 'tic' interrupt. This time is based on the
60hz line frequency and is a low priority interrupt. Apparently, this
interrupt is held off when Transformer runs.
Gene, at what rate does the Transformer lose time? The PC keeps track of
time by counting the number of timer interrupts since the time was initially
set. Timer interrupts are supposed to come at the rate of 18.2
interrupts/second. That might be quite difficult to simulate on the Amiga.
The easiest way to deal with it would be to simulate a PC timer interrupt
after each 3 Amiga "tic" interrupts, thus making 20 interrupts/second.
However, that would make the PC's clock run slightly fast, not slow (each
second, it would add 20 to its timer count, instead of 18 most seconds, and
19 a few; so the clock would run 9.9% fast). If the rate is not consistent,
that's a different story entirely… (Try setting the time, then waiting for
a timed interval (say 1 hour, by kitchen timer), and seeing how much PC time
has elapsed. Then run a PC program that does stuff, and time another hour,
and see how much PC time has elapsed. (Do the first test from the PC-DOS
prompt)). – Bela
Bela, this is not referring to the time loss, but a comment on the 5.25"
drive under AmigaDOS. I know several Amiga users (NCR Engineers) who have
constructed dual 5.25 add on drives that run under AmigaDOS and format 5.25"
diskettes to 880K. These are drives that are call quad density or some such
handle and are able to step the heads in small enough increments to get 80
tracks on the diskettes. When used under the Transformer they will get a DIR
but nothing else. Seems the heads rest over the track with the DIR info. The
last I heard they were working on a switch or board or both, that would cause
the heads to double step and be able to use the normal 40 track MS-DOS
diskettes. All of this leads me to believe that the 5.25 Amiga drive and any
others that are not "quad" cannot step in small enuff steps to format
AmigaDOS on a 5.25 diskette. However, I would think that the latter
PC/MS-DOS that uses the 720K format would work with these drives. – Doug
Rather than brain-damaging those drives, they should write a software driver
that will access them under PC-DOS, as either 360K drives (double sided, 40
tracks, double-stepping the head), or as 720K drives (2s, 80 tracks,
single-stepping the head). Such drivers are commercially available from Tall
Tree Systems, JDrive I believe, but it's questionable whether they'd work
under the Transformer. I know: they should call up Tall Tree and ask them
for an evaluation copy, promising to report back whether they work or not
(which should make it worthwhile for TT).
(If they write the driver, it should follow the PC-DOS tradition of
recognizing the disk type by reading the disk, and adjusting, so that you can
insert either a 360K or a 720K disk in the drive and have it work
automatically. (And it should also support older PC-DOS formats of 160K,
180K and 320K — lots of software is still distributed in those formats)). As
to AmigaDOS on 5.25" drives, you need quad density (80 track) drives to work
with the current AmigaDOS TrackDisk.Device driver. There's absolutely no
reason that AmigaDOS couldn't also support regular 40 track drives, but a new
TrackDisk.Device would have to be written. (It's pretty ironic. The changes
in the driver would probably amount to 5 lines of difference — but until
it's done, you can't use 40 track drives with AmigaDOS). – Bela
I doubt that these guys are interested in using the 5.25's for anything other
than semi-permanent storage under AmigaDOS. They are not the least bit fond
of MS-DOS. They stick a SYS: disk in one and a compiler disk in the other
and then have two 3.5's free for source and etc. Also they LOVE to solve
things with hardware, so I enjoy watching and learning and get a chuckle or
two out of it. – Doug
I doubt that these guys are interested in using the 5.25's for anything other
than semi-permanent storage under AmigaDOS. They are not the least bit fond
of MS-DOS. They stick a SYS: disk in one and a compiler disk in the other
and then have two 3.5's free for source and etc. Also they LOVE to solve
things with hardware, so I enjoy watching and learning and get a chuckle or
two out of it. – Doug
Rather than brain-damaging those drives, they should write a software driver
that will access them under PC-DOS, as either 360K drives (double sided, 40
tracks, double-stepping the head), or as 720K drives (2s, 80 tracks,
single-stepping the head). Such drivers are commercially available from Tall
Tree Systems, JDrive I believe, but it's questionable whether they'd work
under the Transformer. I know: they should call up Tall Tree and ask them
for an evaluation copy, promising to report back whether they work or not
(which should make it worthwhile for TT).
(If they write the driver, it should follow the PC-DOS tradition of
recognizing the disk type by reading the disk, and adjusting, so that you can
insert either a 360K or a 720K disk in the drive and have it work
automatically. (And it should also support older PC-DOS formats of 160K,
180K and 320K — lots of software is still distributed in those formats)). As
to AmigaDOS on 5.25" drives, you need quad density (80 track) drives to work
with the current AmigaDOS TrackDisk.Device driver. There's absolutely no
reason that AmigaDOS couldn't also support regular 40 track drives, but a new
TrackDisk.Device would have to be written. (It's pretty ironic. The changes
in the driver would probably amount to 5 lines of difference — but until
it's done, you can't use 40 track drives with AmigaDOS). – Bela
To eliminate the confusion; First, 40 track drives generally CAN be used with
the Amiga as amiga-type drives. It takes only one piece of software, a format
program. secondly, using 80 track drives as forty track drives also simply
takes a device driver, one that steps twice for every track specified. This
has been done for years on other systems, and we have it working on the Amiga
here. All of these device drivers are complete, and will be released in early
may with out (our) external drive adaptor. –Ben–
To eliminate the confusion; First, 40 track drives generally CAN be used with
the Amiga as amiga-type drives. It takes only one piece of software, a format
program. secondly, using 80 track drives as forty track drives also simply
takes a device driver, one that steps twice for every track specified. This
has been done for years on other systems, and we have it working on the Amiga
here. All of these device drivers are complete, and will be released in early
may with out (our) external drive adaptor. –Ben–
Bela, this is not referring to the time loss, but a comment on the 5.25"
drive under AmigaDOS. I know several Amiga users (NCR Engineers) who have
constructed dual 5.25 add on drives that run under AmigaDOS and format 5.25"
diskettes to 880K. These are drives that are call quad density or some such
handle and are able to step the heads in small enough increments to get 80
tracks on the diskettes. When used under the Transformer they will get a DIR
but nothing else. Seems the heads rest over the track with the DIR info. The
last I heard they were working on a switch or board or both, that would cause
the heads to double step and be able to use the normal 40 track MS-DOS
diskettes. All of this leads me to believe that the 5.25 Amiga drive and any
others that are not "quad" cannot step in small enuff steps to format
AmigaDOS on a 5.25 diskette. However, I would think that the latter
PC/MS-DOS that uses the 720K format would work with these drives. – Doug
Gene, at what rate does the Transformer lose time? The PC keeps track of
time by counting the number of timer interrupts since the time was initially
set. Timer interrupts are supposed to come at the rate of 18.2
interrupts/second. That might be quite difficult to simulate on the Amiga.
The easiest way to deal with it would be to simulate a PC timer interrupt
after each 3 Amiga "tic" interrupts, thus making 20 interrupts/second.
However, that would make the PC's clock run slightly fast, not slow (each
second, it would add 20 to its timer count, instead of 18 most seconds, and
19 a few; so the clock would run 9.9% fast). If the rate is not consistent,
that's a different story entirely… (Try setting the time, then waiting for
a timed interval (say 1 hour, by kitchen timer), and seeing how much PC time
has elapsed. Then run a PC program that does stuff, and time another hour,
and see how much PC time has elapsed. (Do the first test from the PC-DOS
prompt)). – Bela