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t.bamap
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2022-08-26
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BAMAP
=====
Original program from 1541 TEST/DEMO
disk. Author unknown.
Modified by: Joel Ellis Rea
BAMAP reads the BAM from a disk,
and then displays a map of all the
tracks and sectors. Each block that
is allocated is drawn in red, and each
free block is drawn in green. Since
Track 18 holds the directory and the
BAM itself, files cannot be stored on
that track, even of the sectors are
"free". All of Track 18 is set aside
for the directory. BAMAP shows Track
18 as "highlighted", so as to set it
apart from the other tracks.
Note that the innermost tracks have
fewer sectors than the outermost ones.
The BAM is the Block Availability
Map that is part of the directory
header (track 18, sector 0) of every
normal Commodore 1541 format diskette.
It contains a bit for every block on
the disk. That bit shows if the block
is "free" or "allocated". An
allocated block is one that "belongs"
to a file, and is therefore unavail-
able for use. Basically, an allocated
block is "used" and an non-allocated
block is "free".
Bamap is an extensive modification
to the VIEW BAM program on the 1541
TEST/DEMO disk. VIEW BAM was written
for the Vic-20 and has to display the
BAM map in two parts.
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