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⌂ ∞ ▽ Elite on the 6502

Version analysis of CHK2

This code appears in the following versions (click to see it in the source code):

Code variations between these versions are shown below.

       Name: CHK2
       Type: Variable
   Category: Save and load
    Summary: Second checksum byte for the saved commander data file
  Deep dive: Commander save files
             The competition code



 Second commander checksum byte. If the default commander is changed, a new
 checksum will be calculated and inserted by the elite-checksum.py script.

 The offset of this byte within a saved commander file is also shown (it's at
 byte #74).



.CHK2

Code variation 1 of 1Related to the 6502SP version

The Executive version contains a maxed-out default commander, which has a different second checksum byte.

Tap on a block to expand it, and tap it again to revert.

Cassette, Flight, Electron
Master
6502SP
 EQUB &03 EOR &A9       \ The checksum value for the default commander, EOR'd
                        \ with &A9 to make it harder to tamper with the checksum
                        \ byte, #74

 EQUB 0                 \ Placeholder for the checksum in byte #74

IF _SNG45 OR _SOURCE_DISC

 EQUB &03 EOR &A9       \ The checksum value for the default commander, EOR'd
                        \ with &A9 to make it harder to tamper with the checksum
                        \ byte, #74

ELIF _EXECUTIVE

 EQUB &3F EOR &A9       \ The checksum value for the maxed-out default
                        \ commander, EOR'd with &A9 to make it harder to tamper
                        \ with the checksum byte, #74

ENDIF