[Coco] Assembly code scans keyboard but doesn't repeat

[William Astle]

You need a state table to keep track of keys that are pressed. Take a 
look at POLCAT (or "KEYIN" in the color basic unravelled book) to see 
how the Basic ROM does it, though that routine looks are any key press.

On 2017-03-06 03:28 PM, Glen Hewlett wrote:
> Hi All,
>
> Can anyone show me a little assembly code to scan the keyboard for key presses so they don’t repeat?  The code below works for the Up and Down arrows but the keypresses repeat.
>
> Thanks,
> Glen
>
> ScanKeys:
>         LDX     #PIA0_Byte_0_KeyRow_Joy             * PIA0
> ; Up Arrow
>         LDA     #%11110111                          * Bit 3
>         STA     $02,X
>         LDA     ,X
>         BITA    #%00001000                          * and bit 3 = Up Arrow pushed
>         BNE     >                                   * If not, scan for another key
>         LDA     #1
>         STA     MovePointer
>         BRA     CheckedKeys
> ; Down Arrow
> !       LDA     #%11101111                          * Bit 4
>         STA     $02,X
>         LDA     ,X
>         BITA    #%00001000                          * and bit 3 = Down Arrow pushed
>         BNE     >                                   * If not, scan for another key
>         LDA     #2
>         STA     MovePointer
>         BRA     CheckedKeys
> !…
>
>
>