9. Other hints

9.1 Passing arguments to the program

Command line arguments can be passed to main() after BLOAD. Since this is not supported by BASIC, the following syntax was chosen:

]CALL2051:REM ARG1 " ARG2 IS QUOTED" ARG3 "" ARG5

1. Arguments are separated by spaces.
2. Arguments may be quoted.
3. Leading and trailing spaces around an argument are ignored. Spaces within a quoted argument are allowed.
4. The first argument passed to main is the program name.
5. A maximum number of 10 arguments (including the program name) are supported.

9.2 Interrupts

The runtime for the Apple ][ uses routines marked as .INTERRUPTOR for ProDOS 8 interrupt handlers. Such routines must be written as simple machine language subroutines and will be called automatically by the interrupt handler code when they are linked into a program. See the discussion of the .CONDES feature in the assembler manual.

9.3 DIO

Drive ID

The function dio_open() has the single parameter drive_id to identify the drive to be opened. Therefore an Apple II slot and drive pair is mapped to that drive_id according to the formula

drive_id = slot * 16 + (drive - 1) * 128

so that for example slot 6 drive 2 is mapped to drive_id 224.

Sector count

The function dio_query_sectcount() returns the correct sector count for all ProDOS 8 disks. However for any non-ProDOS 8 disk it simply always returns 280 (which is only correct for a 140 KB disk). This condition is indicated by the _oserror value 82.