DD_ENCODE

Categories:

• spectrum
• spectrumAPI

Function	Address	Description
DD_ENCODE	0184	Set copy protection encode routine

Synopsys

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

Always:

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

Always:

AF corrupt, all other registers preserved.