copying 5.25 inch distribution to 3.5 inch.
HC Johnson
hcj at lzsc.ATT.COM
Wed Feb 21 03:29:44 AEST 1990
I've seen reference to problems converting distribution 5.25 disks
to 3.5 inch. This may clarify the situation:
The high Density 3.5 inch disk has 18 sectors on each track, while a
5.25 inch disk has only 15. Under UNIX/386, a floppy is accessed in
two ways; the whole thing (name ends in t), or skip the first cylinder.
The first cylinder is large enough to hold a bootstrap program.
If the Boot disk (1/NN) for the UNIX(r) distribution is copied from
5.25 to 3.5 inches, it must be done in two parts. The boot cylinder
is copied, such as:
dd if=/dev/rdsk/f0q15dt ibs=30b of=/dev/rdsk/f13ht obs=36b count=1
The last 6 sectors of the first cylinder of the 3.5 inch disk has not
been written.
Then the rest of the disk is copied, such as:
dd if=/dev/rdsk/f0q15d ibs=30b of=/dev/rdsk/f13h obs=36b
This copies the remaining 79 cylinders of 2 tracks each.
The other distribution diskettes must be evaluated to see if they start
in the boot area or on cylinder 1. Generally you will expect to see a
cpio or mountable file system on /dev/rdsk/f0q15d. If you find it on (t)
then copy it with the suffix t, otherwise DONT.
Howard C. Johnson
ATT Bell Labs
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att!lzsc!hcj
hcj at lzsc.att.com
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