Commodore 1541-II - Using Random Files (Advanced)

EXAMPLE:
To free the sector in which we wrote our name in the Block Write example, and
allocated in the first Block-Allocate example, we could use the following command:
PRINT#15,"B-F";0;l;l
USING RANDOM FILES (ADVANCED USERS ONLY)
By combining the commands in this chapter, it is possible to develop a file-
handing program that uses random files. What you need to know now is how to
keep track of which blocks on the disk such a file has used. (Even though you know
a sector has not been allocated by your random file, you must also be sure it wasn't
allocated by another unrelated file on the diskette.)
The most common way of recording which sectors have been used by a random file is
in a sequential file. The sequential file stores a list of record numbers, with the track,
sector, and byte location of each record. This means three channels are needed by a
random file: one for the command channel, one for the random data, and the last for the
sequential data.
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