[Coco] Determining OS-9 Floppy Type

[Gene Heskett]

On Saturday 26 May 2007, Andrew wrote:
>As you all know, I am doing a floppy disk conversion project for Carey,
>to rescue a bunch of data from some old floppies, and convert it into
>images which can be read under emulation. I have already completed the
>DECB subset of floppies, and I am beginning to tackle the OS-9 subset.
>
>However, I am running into a snag. When I worked on the DECB subset, I
>was able to determine what kind of disks the OS-9 floppy sides were
>(some of the floppies were "mixed" - one side being DECB, the other
>OS-9) by inference:
>
>Since under OS-9 there are only 35 track SSDD device descriptors and 40
>track DSDD descriptors (but no 40 track SSDD descriptors), if there was
>readable OS-9 data on one side of a floppy and the other was DECB
>formatted (and there were two index holes punched in the floppy jacket),
>then it could only be a 35 track SSDD floppy side.
>
>However, I can't make that inference now since a 35 track SSDD floppy
>(with a single index hole) looks the same physically as a 40 track DSDD
>floppy (which also has a single index hole). Unless it is labeled as a
>certain format, I am not sure how to tell which is which.
>
>Can anyone tell me what the best way of determining whether an OS-9
>formatted floppy is a 35 track SSDD floppy or a 40 track DSDD floppy?
>Whether the method uses DECB, OS-9, or DOS, it doesn't matter. However,
>I don't have access to a Windows machine with a 5.25 floppy drive, so
>that method is out.
>
>I need to know this information so I can make a proper backup and
>recovery image of the floppy (btw - what would be the best way for me to
>create a DSK image of a 40 track DSDD OS-9 floppy under DOS?). Is there
>a way to take an image with each side using RETRIEVE.EXE and then
>combining them somehow? Or, is there something like RETRIEVE.EXE, that
>runs on DOS, that will do this?
>
>Or - could I run a program under DECB in the emulator that took each
>side image and then directly wrote it to a third image using DSKI$ and
>DSKO$? Or perhaps in a similar manner use OS-9 on the emulator to pull
>and combine each image?
>
>Hmm - this conversion effort for the OS-9 floppies has gotten hairy
>quickly. Any and all answers will be appreciated - I don't plan on doing
>anything until I have a working answer from someone(s) out there, or no
>answer is forthcoming and I have to cobble something together myself.
>

Andrew, for os9 there is a very handy utility, called 'dmode'.  With it you 
can adjust a spare descriptor (/d1?) in your bootfile so that it can read 
virtually any format the drive itself can handle.

The arguments you want are 'sid' and 'cyl' which stands for the number of 
sides, and the cylinders/tracks the disk might have.  Note that the value 
for 'cyl' is stated in hexidecimal, so a 40 track disk is 28 in hex, and an 
80 track disk is 50 hex.

>Thank you in advance...
>
>-- Andrew L. Ayers
>    Glendale, Arizona
>
>--
>Coco mailing list
>Coco at maltedmedia.com
>http://five.pairlist.net/mailman/listinfo/coco



-- 
Cheers, Gene
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