Set copy protection encode routine
Function AddressDescription
DD_ENCODE 0184Set copy protection encode routine


Set the copy protection ENCODE subroutine.

Copy protected disks have some of their track and sector numbers encoded on disk. Before each disk access, the ENCODE subroutine is called to encode the physical track and sector numbers.

These encoded track and sector numbers must match those in the sector identifier.

Note that tracks 0…2 on either side of a disk should not be encoded.

Entry Parameters

Register Content
A Enable 0xFF or disable 0x00
HL If enabled address of ENCODE routine

Exit Parameters

HL = Address of previous encode routine, 0 if none
AF BC DE IX corrupt, all other registers preserved.

ENCODE routine

If you are substituting your own ENCODE subroutine, the 'entry conditions' are the conditions passed to your subroutine, and the 'exit conditions' are the values that your subroutine must produce and the registers you are allowed to corrupt.

Entry Parameters

Register Content
C Unit/Side
Bits 0…1 = unit, Bit 2 = side
D Physical track
E Physical sector
IX Address of DPB

Exit Parameters

D = Encoded physical track
E = Encoded physical sector
AF corrupt, all other registers preserved.
Last modified November 24, 2021: Low level operations (85f9e61)