Commodore 1581 - Memory-Execute Command

The following line can be used to recover bad sectors, such as
when an important file has been damaged and cannot be read normally.
PRINT#15,"M-W"CHR$(48)CHR$(0)CHR$(1)CHR$(31)
These two examples may be very useful under some circum
stances. They are the equivalent of POKE 48,133 and POKE 48,31 re
spectively, but in disk memory, not inside the computer. As mentioned
in the previous section's first example, location 48 in the 1581 disk
drive signifies two separate activities to the drive, all related to error
recovery. Bit 7 (the high bit), if set means no "bumps" (don't move the
read head to track 1). The bottom six bits are the count of how many
times the disk will try to read each sector before and after trying seeks
and bumps before giving up. Since 31 is the largest number that can be
expressed in six bits, that is the maximum number of tries allowed.
From this example, you can see the value of knowing something
about Peeks, Pokes, and machine-language before using direct-access
disk commands, as well as their potential power.
MEMOFY-EXECUTE
Any routine in disk memory, either in RAM or ROM, can be ex
ecuted with the MEMORY-EXECUTE command. It is the equivalent of
the BASIC Sys call to a machine language program or subroutine, but
works in disk memory instead of within the computer.
FORMAT FOR THE MEMORY-EXECUTE COMMAND:
PRINT#15,"M-E"CHR$(<address)CHR$(>address)
where "<address" is the low order part, and ">address" is the high or
der part of the address in disk memory at which execution is to begin.
Most uses require intimate knowledge of the inner workings of
the DOS, and preliminary setup with other commands, such as
MEMORY-WRITE.
The routine should end with an RTS to return control to the 1581.
BLOCK-EXECUTE
This rarely-used command will load a sector containing a machine
language routine intxra memory buffer from diskette, and execute it
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