Version analysis of CPIX4 - 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 and Electron

Code variations between these versions are shown below.

       Name: CPIX4
       Type: Subroutine
   Category: Drawing pixels
    Summary: Draw a double-height dot on the dashboard

Code variation 1 of 2A variation in the comments only

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

Cassette, Flight, Docked
6502SP
Electron
 Draw a double-height mode 5 dot (2 pixels high, 2 pixels wide).
 Draw a double-height mode 2 dot (2 pixels high, 2 pixels wide).
 Draw a double-height mode 4 dot (2 pixels high, 4 pixels wide).



 Arguments:

   X1                   The screen pixel x-coordinate of the bottom-left corner
                        of the dot

   Y1                   The screen pixel y-coordinate of the bottom-left corner
                        of the dot

Code variation 2 of 2A variation in the comments only

This variation is blank in the Electron version.

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

Cassette, Flight, Docked
6502SP
   COL                  The colour of the dot as a mode 5 character row byte
   COL                  The colour of the dot as a mode 2 character row byte


.CPIX4

 JSR CPIX2              \ Call CPIX2 to draw a single-height dash at (X1, Y1)

 DEC Y1                 \ Decrement Y1

                        \ Fall through into CPIX2 to draw a second single-height
                        \ dash on the pixel row above the first one, to create a
                        \ double-height dot