Dynamite Dan: Routine at CB9C

CB9C: Set the zero flag if ENTER or the fire button was pressed

Used by the routines at CA5B and DD8D.
CB9C	LD A,($CA5A)	Has Kempston been selected as the input method?
CB9F	CP $09	Has Kempston been selected as the input method?
CBA1	JR NZ,$CBAB	Jump forward if not.
Test for FIRE on Kempston.
CBA3	IN A,($1F)	Read the Kempston joystick.
CBA5	CPL	Invert so successful reads have bits set.
CBA6	BIT 4,A	Was FIRE pressed?
CBA8	RET Z	Return if so.
CBA9	JR $CBB6	Otherwise jump forward.
Test for FIRE on Sinclair.
CBAB	CP $0B	Has Sinclair been selected as the input method?
CBAD	JR NZ,$CBB6	Jump forward if not.
CBAF	LD A,$EF	Read '0' - '6' from the keyboard.
CBB1	IN A,($FE)	Read '0' - '6' from the keyboard.
CBB3	BIT 0,A	Was '0' pressed?
CBB5	RET Z	Return if so.
Test for ENTER on Keyboard.
CBB6	LD A,$BF	Read 'ENTER' - H' from the keyboard.
CBB8	IN A,($FE)	Read 'ENTER' - H' from the keyboard.
CBBA	BIT 0,A	Was 'ENTER' pressed?
CBBC	RET	Return with the zero flag also set if it was.