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⌂ Elite on the BBC Micro

Version analysis of BEGIN

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

Code variations between these versions are shown below.

       Name: BEGIN
       Type: Subroutine
   Category: Loader
    Summary: Initialise the configuration variables and start the game



.BEGIN

Code variation 1 of 4Specific to an individual platform

This variation is blank in the Master version.

Tap on a version to expand it, and tap it again to show to all variations.

Docked
6502SP
 JSR BRKBK              \ Call BRKBK to set BRKV to point to the BRBR routine

\JSR BRKBK              \ This instruction is commented out in the original
                        \ source

Code variation 2 of 4Specific to an individual platform

Tap on a version to expand it, and tap it again to show to all variations.

Docked, 6502SP
Master
 LDX #(CATF-COMC)       \ We start by zeroing all the configuration variables
                        \ between COMC and CATF, to set them to their default
                        \ values, so set a counter in X for CATF - COMC bytes

 LDX #(DTAPE-COMC)      \ We start by zeroing all the configuration variables
                        \ between COMC and DTAPE, to set them to their default
                        \ values, so set a counter in X for DTAPE - COMC bytes

 LDA #0                 \ Set A = 0 so we can zero the variables

.BEL1

 STA COMC,X             \ Zero the X-th configuration variable

 DEX                    \ Decrement the loop counter

 BPL BEL1               \ Loop back to BEL1 to zero the next byte, until we have
                        \ zeroed them all

Code variation 3 of 4Specific to an individual platform

This variation is blank in the Disc (docked) version.

6502SP, Master
 LDA XX21+SST*2-2       \ Set spasto(1 0) to the Coriolis space station entry
 STA spasto             \ from the ship blueprint lookup table at XX21 (so
 LDA XX21+SST*2-1       \ spasto(1 0) points to the Coriolis blueprint)
 STA spasto+1

Code variation 4 of 4Related to the Master version

The Master version contains an embedded copy of the default JAMESON commander file that gets loaded on startup.

This variation is blank in the Disc (docked) and 6502 Second Processor versions.

Master
 JSR JAMESON            \ Call JAMESON to set the last saved commander to the
                        \ default "JAMESON" commander

                        \ Fall through into TT170 to start the game
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