Commodore 1581 - Page 92

FORMAT FOR THE MEMORY-READ COMMAND:
PRINT#15,uM-R"CHR$(<addfess)CHR$(>address)CHR$(# of
bytes)
where "<address" is the low order part, and u>address" is the high
order part of the address in disk memory to be read. If the optional "#
of bytes" is specified, it selects how many memory locations will be
read in, from 1-256 (# of bytes = 0 for 256). Otherwise, 1 character
will be read.
The next byte read using the GET# statement through channel
#15 (the error channel), will be from that address in the disk control
ler's memory, and successive bytes will be from successive memory
locations.
Any INPUT# from the error channel will give peculiar results
when you're using this command. This can be cleared up by sending
any other command to the disk, except another memory command.
EXAMPLES:
To see how many tries the disk will make to read a particular
sector, and whether "bumps" to track one and back will be attempted
before declaring the sector unreadable, you can use the following
lines. They will read a special variable in the zero page of disk
memory, called REVCNT. It is located at $30 hexadecimal.
110 OPEN 15,8,15 Open command channel.
120 PRINT#15/'M-ira IR$(48)CI IR$(0) Same as G = PEEK( 106).
130 GET#15,G$:IF G$ = "" THEN G$ = CIIR$(0)
14OG=ASC(G$)
150 B = G AND 128:B$ = "ON":IF B TIIEN B$ = "OFF" Check bit 7.
170 T=G AND 31:PRINT "# OF TRIES IS";T Check bits 0-5
180 PRINT "BUMPS ARE";B$ and give results.
200 CLOSE 15 Tidy up after.
210 END
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