4Data Telesoftware Adaptor Issue 1.2: Routine at 0FFB

0FFB: toggle_bright: Toggle bright flag.

Used by the routine at handle_keypress.
toggle_bright	0FFB	PUSH AF	Toggle bit 6 of bright_attr (bright bit).
	0FFC	LD A,(bright_attr)
	0FFF	XOR $40
	1001	LD (bright_attr),A
	1004	CALL decode_page	Call decode_page and return.
	1007	POP AF
	1008	RET