| Function | Address | Description |
|---|---|---|
| DOS_MAP_A | 0154 | Map drive B to unit 0 or 1 |
Synopsys
Map drive B: to unit 0 or unit 1. This routine will fail if drive B: has files open.
If mapping B: to unit 0, then each time unit 0 is accessed, a check is made that the drive mapping is correct. If it isn't, then a reverse call to CHANGE DISK is made, to ask the user to change the disk in unit 0.
If mapping B: to unit 1, then if unit 1 does not exist, drive B: is disabled.
Entry Parameters
| Register | Content |
|---|---|
| C | Unit 0 or 1 |
| HL | Address of change disk routine if unit = 0 |
Exit Parameters
- If OK:
- Carry true
- A corrupt
- HL = Address of previous change disk routine, 0 if none
- Otherwise:
- Carry false
- A corrupt
- HL corrupt
- Always:
- BC DE IX corrupt, all other registers preserved.
Change Disk routine
If you are substituting your own CHANGE DISK subroutine, the 'entry conditions' are the conditions passed to your subroutine, and the 'exit conditions' are registers you are allowed to corrupt.
Entry Parameters
| Register | Content |
|---|---|
| A | Logical drive A…P |
| HL | Address of message in page 7 terminated by 0xFF |
Exit Parameters
- Always:
- AF BC DE IX corrupt, all other registers preserved.