The SHIFT subroutine - Elite on the BBC Micro and NES

       Name: SHIFT                                                   [Show more]
       Type: Subroutine
   Category: Keyboard
    Summary: Scan the keyboard to see if SHIFT is currently pressed
    Context: See this subroutine in context in the source code
 References: This subroutine is called as follows:
             * MT26 calls SHIFT


 Returns:

   X                    X = %10000000 if SHIFT is being pressed

                        X = 0 if SHIFT is not being pressed

   A                    Contains the same as X


IF _COMPACT

.SHIFT

 LDA #0                 \ Set A to the internal key number for SHIFT and fall
                        \ through to DKS4mc to scan the keyboard

 EQUB &2C               \ Skip the next instruction by turning it into
                        \ &2C &A9 &49, or BIT &49A9, which does nothing apart
                        \ from affect the flags

ENDIF
Keyboard: SHIFT

[BBC Master version]
