26 Dec
2011
26 Dec
'11
6:29 p.m.
On Mon, 26 Dec 2011, Enrico Lazzerini wrote:
Despite having read the definitions of the FCB manual
on CP / M, I am
finding difficulty in :
1) to determine the block size chosen for different disks;
Find a file directory entry that has only one extent (not strictly
necessary, but takes out some complications), for a file larger than a
few K. Determine the file size (stored as number of 128 byte rcords in
byte 15)
Look at the last 16 bytes of the directory entry, and count how many
entries there are (how many blocks). On a format with less than 256
blocks on the disk, each block number occupies one byte. On a format with
more than 256 blocks on the disk, each block number occupies 2 bytes (and
therefore every other byte of the block list is likely to be 00 until the
disk gets mostly full)