Skip to navigation

⌂ ∞ ▽ Elite on the 6502

Version analysis of COMPAS

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

Code variations between these versions are shown below.

       Name: COMPAS
       Type: Subroutine
   Category: Dashboard
    Summary: Update the compass



.COMPAS

 JSR DOT                \ Call DOT to redraw (i.e. remove) the current compass
                        \ dot

 LDA SSPR               \ If we are inside the space station safe zone, jump to
 BNE SP1                \ SP1 to draw the space station on the compass

 JSR SPS1               \ Otherwise we need to draw the planet on the compass,
                        \ so first call SPS1 to calculate the vector to the
                        \ planet and store it in XX15

Code variation 1 of 1Minor and very low-impact

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

Cassette, Flight, Master, Electron
6502SP
 JMP SP2                \ Jump to SP2 to draw XX15 on the compass, returning
                        \ from the subroutine using a tail call

 BRA SP2                \ Jump to SP2 to draw XX15 on the compass, returning
                        \ from the subroutine using a tail call