Version analysis of CTRL - 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 and Master

Code variations between these versions are shown below.

       Name: CTRL
       Type: Subroutine
   Category: Keyboard
    Summary: Scan the keyboard to see if CTRL is currently pressed


 Returns:

   X                    X = %10000001 (i.e. 129 or -127) if CTRL is being
                        pressed

                        X = 1 if CTRL is not being pressed

   A                    Contains the same as X

Code variation 1 of 1Specific to an individual platform

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

Cassette, Flight, Docked, 6502SP
Master
.CTRL

 LDX #1                 \ Set X to the internal key number for CTRL and fall
                        \ through to DKS4 to scan the keyboard
IF _SNG47

.CTRL

 LDA #1                 \ Set A to the internal key number for CTRL and fall
                        \ through to DKS5 to scan the keyboard

ENDIF