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⌂ ∞ ▽ Elite on the 6502

Version analysis of BRKBK / COLD

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

Code variations between these versions are shown below.

Code variation 1 of 3A variation in the comments only

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

Docked, 6502SP
Master
       Name: BRKBK

       Name: COLD

       Type: Subroutine
   Category: Save and load
    Summary: Set the standard BRKV handler for the game

Code variation 2 of 3A variation in the comments only

This variation is blank in the Disc (docked) and Master versions.

6502SP
 BRKV is set to this routine by the BRKBK routine, which is called by the
 decryption routine at DEEOR just before the game is run for the first time,
 and at the end of the SVE routine after the disc access menu has been
 processed (so this resets BRKV to the standard BRKV handler for the game).

Code variation 3 of 3Specific to an individual platform

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

Docked
Master
6502SP
.BRKBK

 LDA #LO(BRBR)          \ Set BRKV to point to the BRBR routine
 STA BRKV
 LDA #HI(BRBR)
 STA BRKV+1

 RTS                    \ Return from the subroutine

.COLD

 LDA #LO(NEWBRK)        \ Set BRKV to point to the NEWBRK routine
 STA BRKV
 LDA #HI(NEWBRK)
 STA BRKV+1

 LDA #LO(CHPR)          \ Set WRCHV to point to the CHPR routine
 STA WRCHV
 LDA #HI(CHPR)
 STA WRCHV+1

 JSR setzp              \ Call setzp to copy the top part of zero page into
                        \ the buffer at &3000

 JSR SETINTS            \ Call SETINTS to set various vectors, interrupts and
                        \ timers

 JMP SOFLUSH            \ Call SOFLUSH to reset the sound buffers and return
                        \ from the subroutine using a tail call

.BRKBK

 LDA #LO(BRBR)          \ Set BRKV to point to the BRBR routine, disabling
 SEI                    \ interrupts while we make the change and re-enabling
 STA BRKV               \ them once we are done
 LDA #HI(BRBR)
 STA BRKV+1
 CLI

 RTS                    \ Return from the subroutine