Version analysis of LL164 - Elite on the BBC Micro and NES

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.

       Name: LL164
       Type: Subroutine
   Category: Drawing circles
    Summary: Make the hyperspace sound and draw the hyperspace tunnel


 See the IRQ1 routine for details on the multi-coloured effect that's used.


.LL164

Code variation 1 of 4Related to the Master version

The Master version has a unique hyperdrive sound.

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

Cassette, Flight, Docked, 6502SP, Electron
Master
 LDA #56                \ Call the NOISE routine with A = 56 to make the sound
 JSR NOISE              \ of the hyperspace drive being engaged
 LDY #sohyp             \ Call the NOISE routine with Y = 10 to make the first
 JSR NOISE              \ sound of the hyperspace drive being engaged

 LDY #sohyp2            \ Call the NOISE routine with Y = 11 to make the second
 JSR NOISE              \ sound of the hyperspace drive being engaged

Code variation 2 of 4Related to Elite's use of the Tube

This variation is blank in the Master version.

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

Cassette, Flight, Docked
6502SP
Electron
 LDA #1                 \ Set HFX to 1, which switches the screen mode to a full
 STA HFX                \ mode 5 screen, therefore making the hyperspace rings
                        \ multi-coloured and all zig-zaggy (see the IRQ1 routine
                        \ for details)
 LDA #DOhfx             \ Send a #DOhfx 1 command to the I/O processor to tell
 JSR OSWRCH             \ it to show hyperspace colours in the top part of the
 LDA #1                 \ screen
 JSR OSWRCH
 LDA #1                 \ Set HFX to 1. In the other versions, this makes the
 STA HFX                \ hyperspace rings multi-coloured, but the Electron
                        \ version is monochrome, so this has no effect

 LDA #4                 \ Set the step size for the hyperspace rings to 4, so
                        \ there are more sections in the rings and they are
                        \ quite round (compared to the step size of 8 used in
                        \ the much more polygonal launch rings)

Code variation 3 of 4Specific to an individual platform

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

Master
 STA HFX                \ Set HFX to 4, which switches the screen mode to a full
                        \ mode 2 screen, therefore making the hyperspace rings
                        \ multi-coloured and all zig-zaggy (see the IRQ1 routine
                        \ for details)

 JSR HFS2               \ Call HFS2 to draw the hyperspace tunnel rings

Code variation 4 of 4Related to Elite's use of the Tube

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

Cassette, Flight, Docked
Master
6502SP
Electron
 DEC HFX                \ Set HFX back to 0, so we switch back to the normal
                        \ split-screen mode

 RTS                    \ Return from the subroutine
 STZ HFX                \ Set HFX back to 0, so we switch back to the normal
                        \ split-screen mode

 RTS                    \ Return from the subroutine
 LDA #DOhfx             \ Send a #DOhfx 0 command to the I/O processor to tell
 JSR OSWRCH             \ it to show normal colours in the top part of the
 LDA #0                 \ screen, returning from the subroutine using a tail
 JMP OSWRCH             \ call
 DEC HFX                \ Set HFX back to 0, which has no effect in the Electron
                        \ version

 RTS                    \ Return from the subroutine