hcj@lzsc.ATT.COM (HC Johnson) (02/21/90)
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 =====NEW address==== att!lzsc!hcj hcj@lzsc.att.com