TRS-80 Zaps – DOS – MultiDOS

MultiDOS Zaps


Allow Model III v1.7 to boot on a Model 4P

To get v1.7 to boot on a Model 4P you first need to put MODELA/III onto the diskette. Once you do that, make the following zap:

Track 0, sector 1, starting with byte 0 (all values are hexadecimal):

change
F3ED 563A 0243 FE56
to
00FE 113A 0243 FE11

Note: The reason for this is that the Model 4P boot ROM expects the first two bytes to be 00H, FEH, then the hexadecimal track for the directory.


Allow Model III v2.0 to boot on a Model 4P

To get v2.00 to boot on a Model 4P you first need to put MODELA/III onto the diskette. Once you do that, make the following zap:

Track 0, sector 1, starting with byte 0 (all values are hexadecimal):

change
F3
to
00

Note: The reason for this is that the Model 4P boot ROM expects the first two bytes to be 00H, FEH, then the hexadecimal track for the directory.