Read byte from keyboard buffer; shift keyboard buffer; decrease buffer pointer.
Input: –
Output: A = Byte read.
Used registers: A, X, Y.

Query keyboard; put current matrix code into memory address $00CB, current status of shift keys into memory address $028D and PETSCII code into keyboard buffer; handle Commodore-Shift; repeat keys.
Input: –
Output: –
Used registers: A, X, Y.

Read byte from keyboard buffer; shift keyboard buffer; decrease buffer pointer.
Input: –
Output: A = Byte read; 0 = No key press available.
Used registers: A, X, Y.

Update Stop key indicator, at memory address $0091.
Input: –
Output: –
Used registers: A, X.

Query Stop key indicator, at memory address $0091; if pressed, call CLRCHN and clear keyboard buffer.
Input: –
Output: Zero: 0 = Not pressed, 1 = Pressed; Carry: 1 = Pressed.
Used registers: A, X.

SCNKEY. Query keyboard; put current matrix code into memory address $00CB, current status of shift keys into memory address $028D and PETSCII code into keyboard buffer; handle Commodore-Shift; repeat keys.
Input: –
Output: –
Used registers: A, X, Y.
Real address: $EA87.

STOP. Query Stop key indicator, at memory address $0091; if pressed, call CLRCHN and clear keyboard buffer.
Input: –
Output: Zero: 0 = Not pressed, 1 = Pressed; Carry: 1 = Pressed.
Used registers: A, X.
Real address: ($0328), $F6ED.