Function Name: SCNKEY

Purpose: Scan the keyboard
Call address: $FF9F (hex) 65439 (decimal)
Communication registers: None
Preparatory routines: IOINIT
Error returns: None
Stack requirements: 5
Registers affected: A, X, Y

Description: This routine scans the Commodore 64 keyboard and checks for pressed keys. It is the same routine called by the interrupt handler. If a key is down, its ASCII value is placed in the keyboard queue. This routine is called only if the normal IRQ interrupt is bypassed.

How to Use:

1. Call this routine.

EXAMPLE:

   GET  JSR SCNKEY      ;SCAN KEYBOARD
        JSR GETIN       ;GET CHARACTER
        CMP #0          ;IS IT NULL?
        BEQ GET         ;YES... SCAN AGAIN
        JSR CHROUT      ;PRINT IT