Version analysis of SVC - Elite on the 6502

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

Cassette, Disc (flight), Disc (docked), 6502 Second Processor, Master and Electron

Code variations between these versions are shown below.

.SVC

 SKIP 1                 \ The save count
                        \
                        \ When a new commander is created, the save count gets
                        \ set to 128. This value gets halved each time the
                        \ commander file is saved, but it is otherwise unused.
                        \ It is presumably part of the security system for the
                        \ competition, possibly another flag to catch out
                        \ entries with manually altered commander files

 SKIP 2                 \ The commander file checksum
                        \
                        \ These two bytes are reserved for the commander file
                        \ checksum, so when the current commander block is
                        \ copied from here to the last saved commander block at
                        \ NA%, CHK and CHK2 get overwritten

Code variation 1 of 1Specific to an individual platform

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

Cassette, Flight, Docked, 6502SP, Electron
Master
 NT% = SVC + 2 - TP     \ This sets the variable NT% to the size of the current
                        \ commander data block, which starts at TP and ends at
                        \ SVC+2 (inclusive)
 NT% = SVC + 3 - TP     \ This sets the variable NT% to the size of the current
                        \ commander data block, which starts at TP and ends at
                        \ SVC+3 (inclusive), i.e. with the last checksum byte