User`s guide

o- If there is no established default prefix, then, ProDOS will read the volume
name of the volume in the default Slot and Drive.
Note: PREFIX used in this way does not establish or change a pathname prefix.
Booting clears any default prefix and sets default Slot/Drive to the boot drive.
For your STARTUP program to discover the name of the volume on which it resides,
it could execute the following:
100 PRINT CHR$(4)"PREFIX": INPUT"";P$
The volume name of the just booted disk (e.g. "/NARF/") will be saved in P$.
______________________________
From: David Wilson
035- How do I create a folder?
Creating folders (or directories) is the one time you do not need to
provide a type parameter (e.g. TDIR) for the CREATE command. Hence
CREATE GIFPICS
would create a folder named "GIFPICS" in the current default directory.
______________________________
From: Neil Parker
036- How do I access ProDOS routines from machine
language?
You use the ProDOS Machine Language Interface (MLI). The MLI is
responsible for carrying out nearly all of the functions (Read Block, Write
Block, and 24 others) which ProDOS can perform.
Machine language programs call ProDOS by doing a JSR to the MLI at $BF00.
To determine which function to perform, ProDOS examines the "command" byte
immediately following the JSR instruction. Immediately after the command byte
come two more bytes that point to the command's parameter list. When the call
completes, it returns to the code immediately following the parameter list
pointer. A ProDOS MLI call looks something like this:
20 00 BF JSR MLI
80 DB COMMAND_CODE
50 03 DW PARAM_LIST_LOCATION
B0 __ BCS ERROR
In the above, the command code ($80) says "Read a block" and the parameter list
is located at $0350. The MLI call returns with the carry flag set and an error
code in the accumulator if an error occurred; so, a simple error check (the
Branch if Carry Set instruction) is often the next instruction which is
executed.