; Example MIDI program for GT which can be run under MSXDOS(2)
; Written by Alex Wulms for MCCM
; 26-9-1995

UARTsend:	equ	0e8h	; 8251 data send
UARTrecv:	equ	0e8h	; 8251 data receive
UARTcmd:	equ	0e9h	; 8251 command/mode register
UARTstat:	equ	0e9h	; 8251 status register

tm_int:		equ	0eah	; timer interrupt flag off

timer0:		equ	0ech	; 8253 counter 0 dataport
timer1:		equ	0edh	; 8253 counter 1 dataport
timer2:		equ	0eeh	; 8253 counter 2 dataport
tm_cmd:		equ	0efh	; 8253 command

		di
		in	a,(0aah)
		and	0f0h
		or	7
		out	(0aah),a	; select row 7 of keyboard

		ld	a,00010110b	; set timer 0 to
		out	(tm_cmd),a	; generate a square wave
		ld	a,8		; set a frequency
		out	(tm_cmd),a	; of 200 kHz

		ld	hl,UARTdata
		ld	b,6
initUART:	ld	a,(hl)		; initialize UART for
		out	(UARTcmd),a	; MIDI data communication
		inc	hl
		call	waitUART
		djnz	initUART
		in	a,(UARTrecv)	; reset outstanding flags

main:		in	a,(UARTstat)
		and	2		; check RxRDY
		call	nz,midithrough	; data waiting
		in	a,(0a9h)	; read keyboard
		bit	2,a		; check ESC key
		jr	nz,main		; not pressed

		xor	a
		out	(UARTcmd),a	; set MIDI off
		ret			; thats all

waitUART:	in	a,(0e6h)	; wait 4 micro seconds
		ld	c,a		; between two UART operations
waitUART2:	in	a,(0e6h)
		sub	c
		jr	z,waitUART2
		ret

midithrough:	in	a,(UARTrecv)
		ld	b,a		; B = midi IN data
midithr2:	in	a,(UARTstat)
		and	1		; check TxRDY
		jr	z,midithr2	; UART not ready
		ld	a,b
		out	(UARTsend),a	; write to MIDI out
		ret

UARTdata:	db	0,0,0,64,78,5
		db	0,0,0,64,78,5