Robotron: 2084: Routine at 60785

60785: Check Any Key During Display

Used by the routines at Display_High_Score_Entry_Screen, Save_Or_Load_High_Scores and Attract_Mode_Loop. Reads all keyboard rows simultaneously (port 254 with selector 0) during the high score display loop. Forces the upper three bits high; if any key is pressed, increments A past 255 discards the caller's return address, and restarts the high score display at Display_High_Score_Entry_Screen. Returns normally if no keys are held.
Check_Any_Key_During_Display	60785	XOR A	Read all keyboard rows simultaneously.
	60786	IN A,(254)	Read all keyboard rows simultaneously.
	60788	OR %11100000	Force bits 5-7 high.
	60790	INC A	Return if no keys are pressed (A wraps to 0).
	60791	RET Z	Return if no keys are pressed (A wraps to 0).
	60792	POP HL	Discard the caller's return address from the stack.
	60793	JP Display_High_Score_Entry_Screen	Restart the high score display at Display_High_Score_Entry_Screen.