;AY-Voice ----- Thomas Henry
;Last Revision: 7/5/2012 PWH/elmegil

;****************** Constant Definitions ******************
symbol	control	= pinsA				;control lines to the AY chip
symbol	BC1			=	A.0					;A.0 is BC1 on the AY chip
symbol	BDIR		=	A.1					;A.1 is BDIR on the AY chip
symbol	bus			=	pinsB				;data/address bus to AY chip
symbol	buttons	=	pinsC				;C.2-C.5 are arrow buttons

;These are time constants based on a 64 MHz clock. The numbers
;may seem inconsistent since they refer to the pause, pauseus
;or pulsout commands which all use different base units.

symbol	AYpulse		= 4					;2.5 uSec for pulsout
symbol	LCDpulse	=	8					;10 uSec for pauseus
symbol	uSec50		=	40				;50 uSec for pauseus
symbol	mSec			=	8					;1 mSec for pause
symbol	mSec2			=	16				;2 mSec for pause
symbol	mSec10		=	80				;10 mSec for pause
symbol 	mSec50		=	400				;50 mSec for pause
symbol	mSec200		=	1600			;200 mSec for pause
symbol	mSec500		=	4000			;500 mSec for pause
symbol	secOne		=	8000			;one second
symbol	sec3			=	24000			;3 seconds

;AY-8910 control codes and register addresses
symbol	inactive	= %00000000	;data/address bus inactive
symbol	readReg		=	%00000001	;read addressed register
symbol	latchAddr	= %00000011	;latch the address on the DA bus	
symbol	Reg0			=	0					;tone A, coarse (4 bits only)
symbol	Reg1			=	1					;tone A, fine 
symbol	Reg2			=	2					;tone B, coarse (4 bits only)
symbol	Reg3			=	3					;tone B, fine 
symbol	Reg4			=	4					;tone C, coarse (4 bits only)
symbol	Reg5			=	5					;tone C, fine 
symbol	Reg6			=	6					;noise period
symbol	Reg7			=	7					;enable register
symbol	Reg8			=	8					;amplitude A
symbol	Reg9			= 9					;amplitude B
symbol	Reg10			=	10				;amplitude C
symbol	Reg11			=	11				;envelope period LSB
symbol	Reg12			=	12				;envelope period MSB
symbol	Reg13			=	13				;envelope type
symbol	Reg14			=	14				;Port IOA
symbol	Reg15			=	15				;Port IOB
symbol	IOABOut		=	%11000000	;IOA and IOB are outputs

;Here are various LCD commands which can be used.
symbol  clrHome = 1   ;clear the display, home the cursor
symbol  home    = 2   ;home the cursor only
symbol  RtoL    = 4   ;print characters right to left
symbol  insR    = 5   ;insert characters to right
symbol  LtoR    = 6   ;print characters left to right
symbol  insL    = 7   ;insert characters to left
symbol  lcdOff  = 8   ;LCD screen off
symbol  lcdOn   = 12  ;LCD screen on, no cursor
symbol  curOff  = 12  ;an alias for the above
symbol  block   = 13  ;LCD screen on, block cursor
symbol  under   = 14  ;LCD screen on, underline cursor
symbol  undblk  = 15  ;blinking and underline cursor
symbol  panR    = 24  ;pan viewing window right
symbol  panL    = 28  ;pan viewing window left
symbol  mode1   = 32  ;one-line mode (4-bit data)
symbol  mode2   = 40  ;two-line mode (4-bit data)
symbol  bus4    = 32  ;4-bit data bus mode
symbol  bus8    = 48  ;8-bit data bus mode
symbol	uchar		=	64	;start of user-defined character RAM
symbol  line1   = 128 ;go to start of line 1
symbol  line2   = 192 ;go to start of line 2

symbol	unchecked	=	0	;ASCII code for the unchecked box
symbol	checked		=	1	;ASCII code for the checked box

;arrow button values
symbol	up				=	1
symbol	down			=	2
symbol	left			=	3
symbol	right			=	4

;the supported MIDI modes
symbol	mono			=	1
symbol	omni			=	2
symbol	noMIDI		=	3

;checkbox flags
symbol	BoxA			=	4
symbol	BoxB			=	2
symbol	BoxC			=	1	

;envelope types
symbol	AR				=	1			;attack/release
symbol	perc			=	2			;percussive (0 attack)
symbol	eRev			=	3			;reversed (0 release)
symbol	trem			=	4			;tremolo (attack = release, repeats)

;tone frequency limits
symbol	fMin			=	33		;min frequency
symbol	fMax			= 15625	;nax frequency (Hz)
symbol	eMin			= 0			;minimum envelope time
symbol	eMax			= 7999	;maximum envelope time (mS)
symbol	levelMin	=	0			;minimum voice level
symbol	levelMax 	= 15		;maximum voice level
symbol	nMin			=	0			;minimum noise frequency
symbol	nMax			=	31		;maximum noise frequency

; midi values, not all used
symbol MIDI_NOTEOFF = %10000000 
symbol MIDI_NOTEON = %10010000 
symbol MIDI_PAT = %10100000 
symbol MIDI_CTRLCHG = %10110000 
symbol MIDI_PGM = %11000000 
symbol MIDI_CAT = %11010000 
symbol MIDI_MODWHL = %11100000 

;****************** Variable Definitions ******************

symbol	bitFlags	=	w0	;bit flags---unused at present

;AY Voice Parameters - do not use for anything else
symbol	aTime			= w1	;attack time in mSec
symbol	rTime			= w2	;release time in mSec
symbol	toneA			= w3	;tone frequency A
symbol	toneB			= w4	;tone frequency B
symbol	toneC			= w5	;tone frequency C
symbol	tEnable		= b12	;tone enable flags
symbol	nEnable		= b13	;noise enable flags
symbol	eEnable		= b14	;envelope enable flags
symbol	aLevel		= b15	;channel A voice level (0-15)
symbol	bLevel		= b16	;channel B voice level (0-15)
symbol	cLevel		= b17	;channel C voice level (0-15)
symbol	envType		= b18	;AR, tremolo, percussive, reverse
symbol	mode			= b19	;mono, omni, off
symbol	nFreq			= b20	;noise frequency
symbol	base			= b21	;base MIDI channel (1 to 13)

;MIDI variables
symbol 	head   		= w11 ;head of MIDI queue
symbol 	midi   		= b24 ;message byte to be processed
symbol	place			= b24	;(alias) decimal place in number
symbol	dummy			= b25	; unused for now, possible "current channel" ?
symbol  	dataflag		= bit0	; bit flag, used to indicate we have the first data byte of a 2 byte command

;setup mode variables - may be reused with care
symbol	eTime			= w13	;parameter for time print routine
symbol	toneP			= w13 ;(alias) parameter for tone frequency
symbol	periodW		= w13	;(alias) period of wave
symbol	tempW			= w14	;temporary word variable
symbol	powerW		= w14	;(alias) power of ten
symbol	numW			= w15	;number-to-ASCII input parameter
symbol	placeW		= w16	;place value for multiplier
symbol	pMinW			= w17	;parameter minimum value
symbol	pMaxW			= w18	;parameter maximum value
symbol  	char    		= b38 ;ASCII character to be displayed
symbol  	cmd     		= b38 ;(alias) LCD command byte
symbol	temp			= b39	;local variable only for subs
symbol	colSave		= b40	;save old column number
symbol	chrSave		= b40	;(alias) save current character
symbol	arrow			= b41	;current arrow button pressed
symbol	dig4			= b42	;(local) ten-thousands digit in number
symbol	dig3			= b43	;(local) thousands digit in number
symbol	dig2			= b44	;(local) hundreds digit in number
symbol	dig1			= b45	;(local) tens digit in number
symbol	dig0			= b46 ;(local) units digit in number
symbol	row			= b47	;current LCD row
symbol	col			= b48	;current LCD column
symbol	i			= b49	;loop variable
symbol	vLevel		= b50	;level parameter for subroutine
symbol	digits		= b51	;number of digits in string

symbol	ABC			= b42	;(alias) 4=box A, 2=box B, 1=box C
symbol	check			= b43	;(alias) checkbox flag
symbol  	msg   	  	= b44 ;(alias) offset into message table
symbol  	value			= b45 ;(alias) AY register number (0-15)
symbol	register		= b46	;(alias) value to store in AY register

; more midi values
symbol midi_status	= b52
symbol midi_data1		= b53
symbol midi_prev		= b54
symbol midi_current	= b55
symbol midi_lsb		= b28	; (alias) half of tempW, LSB of note
symbol midi_msb		= b29   ; (alias) other half of tempW, MSB of note

;*********************** Messages *************************
eeprom	0,	("AY-VOICE",0)
eeprom	9,	("SETUP MENU",0)
eeprom  20,	("MIDI MODE",0)	
eeprom  30,	("MONO",0)
eeprom  35,	("OMNI",0)		
eeprom  40, ("OFF",0)	
eeprom  44,	("MIDI CHANNEL",0)
eeprom  57, ("TONE ENABLE",0)
eeprom  69, ("NOISE ENABLE",0)
eeprom  82, ("ENVELOPE ENABLE",0)
eeprom  98,	("ENVELOPE TYPE",0)
eeprom  112,("ATTACK/RELEASE",0)
eeprom  127,("PERCUSSIVE",0)
eeprom  138,("REVERSE",0)
eeprom  146,("TREMOLO",0)
eeprom  154,("ENVELOPE TIME",0) 
eeprom  168,("VOICE LEVELS",0)
eeprom  181,("TONE FREQUENCY",0)
eeprom  196,("NOISE FREQUENCY",0)
eeprom	212,("HIT DOWN TO PLAY",0)


;*********************** MIDI Table *************************
;                                note# = table index of LSB
symbol msbOffset = 120		;note# + offset = table index of MSB
symbol noteC1 = 24		;lowest possible note
symbol noteB9 = 131		;highest possible note
;*********************** Note LSB Values *************************
table	24,(238)	;C1
table	25,(24)	;C#1
table	26,(77)	;D1
table	27,(142)	;D#1
table	28,(218)	;E1
table	29,(47)	;F1
table	30,(143)	;F#1
table	31,(247)	;G1
table	32,(104)	;G#1
table	33,(225)	;A1
table	34,(97)	;A#1
table	35,(233)	;B1
table	36,(119)	;C2
table	37,(12)	;C#2
table	38,(167)	;D2
table	39,(71)	;D#2
table	40,(237)	;E2
table	41,(152)	;F2
table	42,(71)	;F#2
table	43,(252)	;G2
table	44,(180)	;G#2
table	45,(112)	;A2
table	46,(49)	;A#2
table	47,(244)	;B2
table	48,(188)	;C3
table	49,(134)	;C#3
table	50,(83)	;D3
table	51,(36)	;D#3
table	52,(246)	;E3
table	53,(204)	;F3
table	54,(164)	;F#3
table	55,(126)	;G3
table	56,(90)	;G#3
table	57,(56)	;A3
table	58,(24)	;A#3
table	59,(250)	;B3
table	60,(222)	;C4
table	61,(195)	;C#4
table	62,(170)	;D4
table	63,(146)	;D#4
table	64,(123)	;E4
table	65,(102)	;F4
table	66,(82)	;F#4
table	67,(63)	;G4
table	68,(45)	;G#4
table	69,(28)	;A4
table	70,(12)	;A#4
table	71,(253)	;B4
table	72,(239)	;C5
table	73,(225)	;C#5
table	74,(213)	;D5
table	75,(201)	;D#5
table	76,(190)	;E5
table	77,(179)	;F5
table	78,(169)	;F#5
table	79,(159)	;G5
table	80,(150)	;G#5
table	81,(142)	;A5
table	82,(134)	;A#5
table	83,(127)	;B5
table	84,(119)	;C6
table	85,(113)	;C#6
table	86,(106)	;D6
table	87,(100)	;D#6
table	88,(95)	;E6
table	89,(89)	;F6
table	90,(84)	;F#6
table	91,(80)	;G6
table	92,(75)	;G#6
table	93,(71)	;A6
table	94,(67)	;A#6
table	95,(63)	;B6
table	96,(60)	;C7
table	97,(56)	;C#7
table	98,(53)	;D7
table	99,(50)	;D#7
table	100,(47)	;E7
table	101,(45)	;F7
table	102,(42)	;F#7
table	103,(40)	;G7
table	104,(38)	;G#7
table	105,(36)	;A7
table	106,(34)	;A#7
table	107,(32)	;B7
table	108,(30)	;C8
table	109,(28)	;C#8
table	110,(27)	;D8
table	111,(25)	;D#8
table	112,(24)	;E8
table	113,(22)	;F8
table	114,(21)	;F#8
table	115,(20)	;G8
table	116,(19)	;G#8
table	117,(18)	;A8
table	118,(17)	;A#8
table	119,(16)	;B8
table	120,(15)	;C9
table	121,(14)	;C#9
table	122,(13)	;D9
table	123,(13)	;D#9
table	124,(12)	;E9
table	125,(11)	;F9
table	126,(11)	;F#9
table	127,(10)	;G9
table	128,(9)	;G#9
table	129,(9)	;A9
table	130,(8)	;A#9
table	131,(8)	;B9


;*********************** Note MSB Values *************************

table	144,	(14)	;C1
table	145,	(14)	;C#1
table	146,	(13)	;D1
table	147,	(12)	;D#1
table	148,	(11)	;E1
table	149,	(11)	;F1
table	150,	(10)	;F#1
table	151,	(9)	;G1
table	152,	(9)	;G#1
table	153,	(8)	;A1
table	154,	(8)	;A#1
table	155,	(7)	;B1
table	156,	(7)	;C2
table	157,	(7)	;C#2
table	158,	(6)	;D2
table	159,	(6)	;D#2
table	160,	(5)	;E2
table	161,	(5)	;F2
table	162,	(5)	;F#2
table	163,	(4)	;G2
table	164,	(4)	;G#2
table	165,	(4)	;A2
table	166,	(4)	;A#2
table	167,	(3)	;B2
table	168,	(3)	;C3
table	169,	(3)	;C#3
table	170,	(3)	;D3
table	171,	(3)	;D#3
table	172,	(2)	;E3
table	173,	(2)	;F3
table	174,	(2)	;F#3
table	175,	(2)	;G3
table	176,	(2)	;G#3
table	177,	(2)	;A3
table	178,	(2)	;A#3
table	179,	(1)	;B3
table	180,	(1)	;C4
table	181,	(1)	;C#4
table	182,	(1)	;D4
table	183,	(1)	;D#4
table	184,	(1)	;E4
table	185,	(1)	;F4
table	186,	(1)	;F#4
table	187,	(1)	;G4
table	188,	(1)	;G#4
table	189,	(1)	;A4
table	190,	(1)	;A#4
table	191,	(0)	;B4
table	192,	(0)	;C5
table	193,	(0)	;C#5
table	194,	(0)	;D5
table	195,	(0)	;D#5
table	196,	(0)	;E5
table	197,	(0)	;F5
table	198,	(0)	;F#5
table	199,	(0)	;G5
table	200,	(0)	;G#5
table	201,	(0)	;A5
table	202,	(0)	;A#5
table	203,	(0)	;B5
table	204,	(0)	;C6
table	205,	(0)	;C#6
table	206,	(0)	;D6
table	207,	(0)	;D#6
table	208,	(0)	;E6
table	209,	(0)	;F6
table	210,	(0)	;F#6
table	211,	(0)	;G6
table	212,	(0)	;G#6
table	213,	(0)	;A6
table	214,	(0)	;A#6
table	215,	(0)	;B6
table	216,	(0)	;C7
table	217,	(0)	;C#7
table	218,	(0)	;D7
table	219,	(0)	;D#7
table	220,	(0)	;E7
table	221,	(0)	;F7
table	222,	(0)	;F#7
table	223,	(0)	;G7
table	224,	(0)	;G#7
table	225,	(0)	;A7
table	226,	(0)	;A#7
table	227,	(0)	;B7
table	228,	(0)	;C8
table	229,	(0)	;C#8
table	230,	(0)	;D8
table	231,	(0)	;D#8
table	232,	(0)	;E8
table	233,	(0)	;F8
table	234,	(0)	;F#8
table	235,	(0)	;G8
table	236,	(0)	;G#8
table	237,	(0)	;A8
table	238,	(0)	;A#8
table	239,	(0)	;B8
table	240,	(0)	;C9
table	241,	(0)	;C#9
table	242,	(0)	;D9
table	243,	(0)	;D#9
table	244,	(0)	;E9
table	245,	(0)	;F9
table	246,	(0)	;F#9
table	247,	(0)	;G9
table	248,	(0)	;G#9
table	249,	(0)	;A9
table	250,	(0)	;A#9
table	251,	(0)	;B9




;********************** Main Program **********************
pgm:
 	setfreq em64								;64 MHz external resonator
  dirsA = %00001111						;A.0-A.3 are outputs
  dirsB = %11111111						;B.0-B.7 are normally outputs
  dirsC = %00000011						;C.2-C.7 are inputs
   
  pwmout C.1,7,16							;start AY clock at 2 MHz
  head = 0             				;initialize queue
  mode = mono									;mono mode by default
  base = 0										;base channel for MIDI
  envType = AR								;attack/release at the outset
  toneA = fMin								;tone frequencies at minimum
  toneB = fMin
  toneC = fMin
  
	gosub init									;initialize AY and LCD
	gosub makeChrs							;create user-defined characters
	
; for MIDI testing, in place of menus, I'm setting additional defaults directly

;----- Tone Enable Menu	-----			
		
	tEnable = %00000000		; disable all

	register = reg7						;read enable register
	gosub fetch								;get current stored value
	
	check = not tEnable				;complement tone enable flags
	check = check rev 3	 			;reverse order of A, B and C
	check = check & %00000111	;mask off any junk
	value = value & %11111000	;strip A, B and C off
	value = value | check			;factor in the flags
	gosub store								;and store new result

;----- Noise Enable Menu -----				
		
	nEnable = %00000000		; disable all
	
	register = reg7						;enable register
	gosub fetch								;get current stored value
	
	check = not nEnable				;complement the bits
	check = check rev 3				;reverse order of A, B and C
	check = check << 3				;shift left three bits
	check = check & %00111000	;mask off junk
	value = value & %11000111	;strip out A, B and C
	value = value | check			;factor in the flags
	gosub store								;and store new result	

;----- Envelope Enable Menu -----				

	eEnable = %00000000					;update them
	
	register = reg8						;get amplitude A
	gosub fetch
	
	ABC = check & %00000100		;get A flag
	ABC = ABC << 2						;shift to enable bit position
	value = value & %11101111	;remove old flag
	value = value | ABC				;pop in the new one
	gosub store
	
	register = reg9						;get amplitude B
	gosub fetch
	
	ABC = check & %00000010		;get B flag
	ABC = ABC << 3						;shift to enable bit position
	value = value & %11101111	;remove old flag
	value = value | ABC
	gosub store	
	
	register = reg10					;get amplitude C
	gosub fetch
	
	ABC = check & %00000001		;get C flag
	ABC = ABC << 4						;shift to enable bit position
	value = value & %11101111	;remove old flag
	value = value | ABC
	gosub store		

;----- Envelope Type Menu -----
		
	aLevel = levelMax
	register = reg8						;get amplitude A
	gosub fetch
	value = value & %11110000	;remove old level
	value = value | aLevel		;factor in new level
	gosub store	
	
	bLevel = levelMax
	register = reg9						
	gosub fetch
	value = value & %11110000	;remove old level
	value = value | bLevel
	gosub store			

	cLevel = levelMax
	register = reg10					
	gosub fetch
	value = value & %11110000	;remove old level
	value = value | cLevel
	gosub store			

;----- Tone Frequency Menus -----
; defaults are already fMin, but need to store them

	periodW = toneA / 2					;compute the period
	periodW = 62500 / periodW
	value = periodW % 256				;store fine tune
	register = reg0						
	gosub store

	value = periodW / 256				;store coarse tune
	register = reg1						
	gosub store

	
	periodW = toneB / 2					;compute the period
	periodW = 62500 / periodW
	value = periodW % 256				;store fine tune
	register = reg2						
	gosub store

	value = periodW / 256				;store coarse tune
	register = reg3						
	gosub store
	
	periodW = toneC / 2					;compute the period
	periodW = 62500 / periodW
	value = periodW % 256				;store fine tune
	register = reg4						
	gosub store

	value = periodW / 256				;store coarse tune
	register = reg5						
	gosub store

; End of setting/storing defaults
; Start of MIDI
	hsersetup B31250_64,%00001001 ;turn on MIDI input  doing here so we don't have a big backlog before we get the rest of setup done
	midi_status = 0	; required for proper functioning of process_midi
	dataflag = 0	; possibly unnecessary to set 0 here
	midi_prev = $FF	; previous note, $FF is not valid, no previous note saved
	midi_current = $FF ; current note, top of stack, $FF is all notes off
        main:
          if head != hserptr then       ;anything in queue?
            ptr = head                                          ;yes
            midi = @ptrinc                              ;get the byte
            head = ptr                                          ;move head one byte along

            if head = 1024 then             ;but don't go beyond end
                    head = 0                                                ;wrap around
            endif
	      gosub process_midi
          endif
        goto main                     ;repeat forever (obviously we want a way to escape to the menu should we need to)

end													;end of main program


;************************************************************* 
;*                                                           * 
;*   Process MIDI byte                                * 
;*   Input parameters:      midi                                 * 
;*   Static variables:   midi_status (must be=0 at startup), midi_data1                        * 
;*   Local variables:      temp                                 * 
;*                                                           * 
;************************************************************* 

process_midi: 
  if midi >= %10000000 then   ;status byte 
    ;SerTxd("status byte", CR, LF)
    if midi >= %11110000 then   ;system common 
      ;SerTxd("	system common", CR, LF)
      if midi >= %11111000 then goto sys_rt 	;ignore all other system common msgs, including sysex 
      midi_status = 0      ;reset running status 
      SerTxd("		reset running status", CR, LF)
    else    ;channel message 
      ;check channel, if not ours set midi_status = 0 
      midi_status = 0
      temp = midi & %00001111	; mask off the channel number
      for i = 0 to 3
        check = base + i	; reusing check variable
        if temp = check then
          midi_status = midi 	; we have a winner!
        endif
        next i
      midi_data1 = 0
      dataflag = 0
    endif 
  else      ;data byte 
    if midi_status > 0 then   ;status sent or valid running status 
      temp = midi_status & %11110000 

      ;the following messages require 1 data byte, which we just got 
      if temp = MIDI_PGM then goto prog_change 
      if temp = MIDI_CAT then goto chan_atouch 

      ;the following messages require 2 data bytes 
      if dataflag = 0 then  ; first byte, but we need another one 
        midi_data1 = midi 
	  dataflag = 1	; got our first byte flag
      else 
	  dataflag = 0	; got our second byte, flip the flag back
        if temp = MIDI_NOTEON then goto note_on 
        if temp = MIDI_NOTEOFF then goto note_off 
        if temp = MIDI_CTRLCHG then goto control_change 
        if temp = MIDI_MODWHL then goto mod_wheel 
        if temp = MIDI_PAT then goto poly_atouch 
      endif 
    ;else ignore 
    endif
  endif 
return 

; for the moment ignoring the nuances of voiceA/voiceB/voiceC/Gates
; all changes go only to voiceA
note_on: 
  ;note=midi_data1, vel=midi
  if midi = 0 then goto note_off 
  SerTxd("Note On, Note #", #midi_data1,9, " vel ", #midi,9,CR,LF)
  SerTxd(" On Entry, Prev was ", #midi_prev, " and Current was ", #midi_current,CR,LF)
  midi_prev = midi_current
  midi_current = midi_data1
note_on2:				; entry from note_off for trill
  ; handle out of range notes
  if midi_data1 < noteC1 or midi_data1 > noteB9 then
    ; ERROR out of range!
  else
    ;process note on here 
    temp = midi_data1 + msbOffset
    readtable midi_data1, midi_lsb
    readtable temp, midi_msb
    ;SerTxd("	MSB ", #midi_msb, " LSB ", #midi_lsb,CR,LF)
    register = 0
    value = midi_lsb
    gosub store
    register = 1
    value = midi_msb
    gosub store
  
    tEnable = %00000100		; enable A

    register = reg7						;read enable register
    gosub fetch								;get current stored value
	
    check = not tEnable				;complement tone enable flags
    check = check rev 3	 			;reverse order of A, B and C
    check = check & %00000111	;mask off any junk
    value = value & %11111000	;strip A, B and C off
    value = value | check			;factor in the flags
    gosub store			
    ; should have actual generate trigger here
  midi_data1 = 0
  SerTxd(" On Exit, Prev is ", #midi_prev, " and Current is ", #midi_current,CR,LF)
  endif
return 

note_off: 
  ;note=midi_data1, vel=midi 
  SerTxd("Note Off, Note #", #midi_data1,9, " vel ", #midi,9,CR,LF)
  SerTxd(" On Entry, Prev was ", #midi_prev, " and Current was ", #midi_current,CR,LF)
  if midi_data1 < noteC1 or midi_data1 > noteB9 then
    ; ERROR out of range!
  else
    if midi_data1 = midi_current then
      midi_current = midi_prev
      midi_prev = $FF
      if midi_current <> $FF then
        midi_data1 = midi_current
        SerTxd(" Going to trill with note ", #midi_data1,CR,LF)
        goto note_on2
      else
        ;process note off here 
    	  tEnable = %00000000		; disable all

    	  register = reg7						;read enable register
    	  gosub fetch								;get current stored value
	
    	  check = not tEnable				;complement tone enable flags
    	  check = check rev 3	 			;reverse order of A, B and C
    	  check = check & %00000111	;mask off any junk
    	  value = value & %11111000	;strip A, B and C off
    	  value = value | check			;factor in the flags
    	  gosub store		
      endif
    else		; note off is either prev or before note
    	if midi_data1 = midi_prev then ; previous note turning off, don't turn off current
    	   midi_prev = $FF		 ; but take prev out of the stack
    	;else the note turning off is prior to previous note, ignore it
     	endif
    endif
  endif
  midi_data1 = 0
  SerTxd(" On Exit, Prev is ", #midi_prev, " and Current is ", #midi_current,CR,LF)
return 

; from here out, aside from clearing midi_data bytes, nothing tested
;unhandled MIDI msgs (fill-in as appropriate) 
poly_atouch: 
  ;note=midi_data1, value=midi
control_change: 
  ;control=midi_data1, value=midi
mod_wheel: 
  ;lsb=midi_data1, msb=midi
  midi_data1 = 0
return 

prog_change: 
  ;prog=midi 
chan_atouch: 
  ;value=midi 
sys_rt: 
  ;msg=midi 
  midi_data1 = 0 ; possibly redundant/unnecessary
return 


;*************************************************************
;*                                                           *
;*	Initialize AY and LCD on power-up                        *
;*	Input parameters:		none                                 *
;*	Output parameters:	none                                 *
;*	Local variables:		i                                    *
;*                                                           *
;*************************************************************

init:
  control = inactive				;clear BC1, BDIR

  ;set up the AY Port IOB for output
  control = latchAddr				;latch address to register 7
  bus = Reg7								
  control = inactive
  bus = IOABOut							;make IOA and IOB all outputs
  pulsout BDIR,AYpulse		
 
init2:  
  pause mSec200							;let LCD settle for 200 mS at power-up 
  control = latchAddr				;latch address to register 15
  bus = Reg15								
  control = inactive
  
  bus = %00100011						;set to 8-bit mode
  pulsout BDIR,AYPulse			
  bus = %00000011						
  pulsout BDIR,AYPulse  
	pause mSec10  						;pause a bit
  
  for i = 1 to 2						;send twice more for security
  	bus = %00100011					
	  pulsout BDIR,AYPulse			
	  bus = %00000011						
	  pulsout BDIR,AYPulse  
	next i

  for i= 1 to 2
	  bus = %00100010					;set to 4-bit mode
	  pulsout BDIR,AYPulse			
	  bus = %00000010						
	  pulsout BDIR,AYPulse  
	next i  
  
  bus = %00101000						;set to 2-line mode
  pulsout BDIR,AYPulse			
  bus = %00001000						
  pulsout BDIR,AYPulse  
	pause mSec10  
	
 	cmd = lcdOn								;display on, no cursor
	gosub sendCmd
	pauseus uSec50
return

;*************************************************************
;*                                                           *
;*	Send a Character to the LCD, RS must be high             *
;*	Input parameters:		char                                 *
;*	Output parameters:	none                                 *
;*	Local variables:		temp                                 *
;*                                                           *
;*************************************************************

sendChr:
  control = latchAddr			;latch address mode
  bus = Reg15							;access Port IOB
  control = inactive			;address now latched
  temp = char >> 4		 		;shift high nibble right 
  bus = temp | %00110000 	;Enable high (and RS)
  pulsout BDIR,AYpulse		;latch data
  pause LCDpulse					;keep high for 200 uS
	bus = temp | %00010000  ;Enable low, RS still high
  pulsout BDIR,AYpulse		;latch data
	
  temp = char & %00001111	;grab low nibble 
  bus = temp | %00110000	;Enable high,RS high  
  pulsout BDIR,AYPulse		;latch data
  pause LCDpulse
  bus = temp | %00010000	;Enable low
  pulsout BDIR,AYPulse		;latch data
return

;*************************************************************
;*                                                           *
;*	Send a command to the LCD, RS must be low                *
;*	Input parameters:		cmd                                  *
;*	Output parameters:	none                                 *
;*	Local variables:		temp                                 *
;*                                                           *
;*************************************************************

sendCmd:
  control = latchAddr			;latch address mode
  bus = Reg15							;access Port IOB
  control = inactive			;address now latched
  temp = cmd >> 4		 			;shift high nibble right 
  bus = temp | %00100000 	;Enable high,RS low
  pulsout BDIR,AYpulse		;latch data
  pause LCDpulse
	bus = temp						  ;Enable low, RS still low
  pulsout BDIR,AYpulse		;latch data

	temp = char & %00001111	;grab low nibble 
  bus = temp | %00100000	;Enable high,RS low  
  pulsout BDIR,AYPulse		;latch data
	pause LCDpulse
  bus = temp							;Enable low, RS still low
  pulsout BDIR,AYPulse		;latch data
  pause mSec							;commands take longer
return

;*************************************************************
;*                                                           *
;*	Clear LCD and home cursor                                *
;*	Input parameters:		none                                 *
;*	Output parameters:	row=0, col=0                         *
;*	Local variables:		none                                 *
;*                                                           *
;*************************************************************

clr:
  cmd = clrHome					;clear display and home cursor
  gosub sendCmd					
  pause mSec2						;clear LCD takes longer to execute	
  row = 0
  col = 0
return  

;*************************************************************
;*                                                           *
;*	Clear line two only                                      *
;*	Input parameters:		none                                 *
;*	Output parameters:	row=1, col=0                         *
;*	Local variables:		i                                    *
;*                                                           *
;*************************************************************

clrLine2:
	cmd = line2						;put cursor on second row
	gosub sendCmd
	
	char = " "						;blank it out
	for i = 1 to 16
		gosub sendChr
	next i
	
	row = 1								;put cursor at start of row
	col = 0
	gosub locate
return	

;*************************************************************
;*                                                           *
;*	Create the two user-defined characters                   *
;*	Input parameters:		none                                 *
;*	Output parameters:	none                                 *
;*	Local variables:		i                                    *
;*                                                           *
;*************************************************************

makeChrs:
	cmd = uchar					;point to start of user character RAM
	gosub sendCmd
	
	char = %00000				;unchecked box
	gosub sendChr
	char = %11111
	gosub sendChr
	char = %10001
	for i = 1 to 3
		gosub sendChr
	next i
	char = %11111
	gosub sendChr
	char = %00000
	gosub sendChr
	gosub sendChr
	
	gosub sendChr				;checked box
	char = %11111
	for i = 1 to 5
		gosub sendChr
	next i
	char = %00000
	gosub sendChr
	gosub sendChr
return		

;*************************************************************
;*                                                           *
;*	Place the cursor in desired location                     *
;*	Input parameters:		row, col                             *
;*	Output parameters:	none                                 *
;*	Local variables:		temp                                 *
;*                                                           *
;*************************************************************

locate:
	if row = 0 then			;choose the row
  	temp = line1
  else
  	temp = line2
  endif		
  
  cmd = temp+col  		;factor in the column               
  gosub sendCmd  
return

;*************************************************************
;*                                                           *
;*	Print message to the LCD                                 *
;*	Input parameters:		msg, row, col                        *
;*	Output parameters:	none                                 *
;*	Local variables:		none                                 *
;*                                                           *
;*************************************************************

printMsg:
	gosub locate

  read msg,char					;prime the loop
  do while char != 0		;null terminates the string
  	gosub sendChr
  	inc msg
		read msg,char  	
  loop	
return

;*************************************************************
;*                                                           *
;*	Print a two-digit number                                 *
;*	Input parameters:		numW                                 *
;*	Output parameters:	none                                 *
;*	Local variables:		dig4, dig3, dig2, dig1, dig0         *
;*                                                           *
;*************************************************************

printNum2:
  bintoASCII numW,dig4, dig3, dig2, dig1, dig0 
  goto printNum5c

;*************************************************************
;*                                                           *
;*	Print a four-digit number                                *
;*	Input parameters:		numW                                 *
;*	Output parameters:	none                                 *
;*	Local variables:		dig4, dig3, dig2, dig1, dig0         *
;*                                                           *
;*************************************************************

printNum4:
  bintoASCII numW,dig4, dig3, dig2, dig1, dig0 
  goto printNum5b

;*************************************************************
;*                                                           *
;*	Print a five-digit number                                *
;*	Input parameters:		numW                                 *
;*	Output parameters:	none                                 *
;*	Local variables:		dig4, dig3, dig2, dig1, dig0         *
;*                                                           *
;*************************************************************

printNum5:
  bintoASCII numW,dig4, dig3, dig2, dig1, dig0 
  char = dig4
  gosub sendChr
  
printNum5b:
  char = dig3
  gosub sendChr
  
  char = dig2
  gosub sendChr
  
printNum5c:
  char = dig1
  gosub sendChr
  char = dig0
  gosub sendChr
return

;*************************************************************
;*                                                           *
;*	Print single envelope time                               *
;*	Input parameters:		eTime, char (A or R)                 *
;*	Output parameters:	none                                 *
;*	Local variables:		numW                                 *
;*                                                           *
;*************************************************************

printTime:
  gosub sendChr			;print the letter label
  char = ":"
  gosub sendChr
  numW = eTime 		
  gosub printNum4		;0000 to 7999 milliseconds
return

;*************************************************************
;*                                                           *
;*	Print both envelope times                                *
;*	Input parameters:		none                                 *
;*	Output parameters:	none                                 *
;*	Local variables:		eTime                                *
;*                                                           *
;*************************************************************

printTimes:
	gosub clrLine2		;print attack time
	char = "A"
	eTime = aTime
	gosub printTime
	
	col = 10					;print release time
	gosub locate
	char = "R"
	eTime = rTime
	gosub printTime	
return

;*************************************************************
;*                                                           *
;*	Get an envelope time                                     *
;*	Input parameters:		eTime, col                           *
;*	Output parameters:	eTime, arrow (L/R only)              *
;*	Local variables:		digits, numW, pMaxW, pMinW           *
;*                                                           *
;*************************************************************

getTime:
	gosub locate									;sit on leftmost digit
	
getTime1:
	numW = eTime 									;show current time
	gosub printNum4								;print it
	digits = 4										;four digit number input	
	pMaxW = eMax									;max envelope time in mS
	pMinW = eMin									;min envelope time in mS
	gosub getNum									;fetch new number
	eTime = numW									;update new result
return	
	  	  		
;*************************************************************
;*                                                           *
;*	Display Voice Levels                                     *
;*	Input parameters:		none                                 *
;*	Output parameters:	none                                 *
;*	Local variables:		none                                 *
;*                                                           *
;*************************************************************	
	  	  			  	  		
printLevels:
	gosub clrLine2
	char = "A"
	gosub sendChr							;print the channel letter
	char = ":"
	gosub sendChr							;then a colon
	numW = aLevel
	gosub printNum2						;and finally the level

	char = " "								;two spaces
	gosub sendChr
	gosub sendChr
	
	char = "B"								;repeat for B
	gosub sendChr							
	char = ":"
	gosub sendChr							
	numW = bLevel
	gosub printNum2		
	
	char = " "								
	gosub sendChr
	gosub sendChr
	
	char = "C"								;and now C
	gosub sendChr							
	char = ":"
	gosub sendChr							
	numW = cLevel
	gosub printNum2
return							
		  	  			  				
;*************************************************************
;*                                                           *
;*	Get a Voice Level                                        *
;*	Input parameters:		vLevel, row, col                     *
;*	Output parameters:	vLevel, arrow (L/R)                  *
;*	Local variables:		numW, digits, pMinW, pMaxW           *
;*                                                           *
;*************************************************************	
	  		  	  			  	  		
getLevel:
	gosub locate							;locate on the tens digit
	cmd = block								;blink cursor
	gosub sendCmd
													
	numW = vLevel							;pass in current value
	digits = 2								;a two-digit number only
	pMinW = levelMin
	pMaxW = levelMax
	
	gosub getNum							;get new value
	vLevel = numW							;update the level
return		  		

;*************************************************************
;*                                                           *
;*	Get a Voice Frequency                                    *
;*	Input parameters:		toneP, row, col                      *
;*	Output parameters:	toneP, arrow (L/R)                   *
;*	Local variables:		numW, digits, pMinW, pMaxW           *
;*                                                           *
;*************************************************************	
	  		  	  			  	  		
getFreq:
	gosub clrLine2						;print current value
	numW = toneP
	gosub printNum5
	char = " "
	gosub sendChr
	char = "H"
	gosub sendChr
	char = "z"
	gosub sendChr
		
	col = 0	
	digits = 5								;a five-digit number
	pMinW = fMin
	pMaxW = fMax
	gosub getNum							;get new value
	toneP = numW							;update the frequency
return		  		

;***************************************************************
;*                                                             *
;*	Get a decimal digit                                        *
;*	Input parameters:		numW, col, digits, place, pMaxW, pMinW *
;*	Output parameters:	numW, arrow (L/R only)                 *
;*	Local variables:		powerW, i                              *
;*                                                             *
;***************************************************************
;
;digits = how many digits in the number
;place  = which digit to work on (1=units, 2=hundreds, etc.)
;col    = position of leftmost digit in the number

getDigit:
	colSave = col									;save start of number pointer
	
getDigit2:	
	col = col + digits - place
	gosub locate									;place cursor on digit
	
	powerW = 1										;create power of ten
	i = place
	do while i > 1
		powerW = 10 * powerW
		dec i
	loop	
	
	gosub getKey
	if arrow = left then					;exit and go to previous 
		goto getDigit3
	endif
	if arrow = right then					;exit and go to next
		goto getDigit3
	endif

	if arrow = up then						;else change number
		numW = numW + powerW				
	else
		if numW >= powerW then			;safe to decrement
			numW = numW - powerW min pMinW
		endif	
	endif

	if numW > pMaxW then					;got too big
		numW = numW - powerW				;so undo	
	endif

	col = colSave									;restore column pointer
	gosub locate									;update the display
	if digits = 5 then
		gosub printNum5
	elseif digits = 4 then
		gosub printNum4
	else
		gosub printNum2
	endif	
	goto getDigit2
getDigit3:
	col = colSave
	return
	  		 
;*************************************************************
;*                                                           *
;*	Get a two, four or five digit number                     *
;*	Input parameters:		numW, col, digits, pMaxW, pMinW      *
;*	Output parameters:	numW, arrow (L/R only)               *
;*	Local variables:		place                                *
;*                                                           *
;*************************************************************

getNum:
	cmd = block										;blink the cursor
	gosub sendCmd
	
	if digits = 4 then						;handle four digits
		goto getNum2
	elseif digits = 2 then				;or two digits
		goto getNum4
	endif													;otherwise five digits	

getNum1:
	place = 5											;handle 10000s digit
	gosub getDigit
	
	if arrow = left then					;exit and go to previous menu
		goto getNum6
	endif
	if arrow = right then					;go to next digit
		goto getNum2
	endif
	
	goto getNum1
	
getNum2:
	place = 4											;handle 1000s digit
	gosub getDigit
	
	if arrow = left then
		if digits = 5 then
			goto getNum1							;5 digits, previous digit
		else
			goto getNum6							;4 digits, previous menu
		endif	
	endif
	if arrow = right then					;go to next digit
		goto getNum3
	endif
	
	goto getNum2
	
getNum3:
	place = 3											;handle 100s digit
	gosub getDigit
	
	if arrow = left then					;exit and go to previous digit
		goto getNum2
	endif
	if arrow = right then					;go to next digit
		goto getNum4
	endif
	
	goto getNum3
	
getNum4:
	place = 2											;handle 10s digit
	gosub getDigit
	
	if arrow = left then					
		if digits > 2 then
			goto getNum3							;5 or 4 digits, previous digit
		else
			goto getNum6							;2 digits, previous menu
		endif
	endif
	
	if arrow = right then					;go to next digit
		goto getNum5
	endif
	
	goto getNum4	
	
getNum5:
	place = 1											;handle ones digit
	gosub getDigit
	
	if arrow = left then					;exit and go to previous digit
		goto getNum4
	endif
	if arrow = right then					;go to next menu
		goto getNum6
	endif
	
	goto getNum5

getNum6:
	cmd = curOff
	gosub sendCmd
	return
	  	 	  			  	  		
;*************************************************************
;*                                                           *
;*	Do the checkboxes                                        *
;*	Input parameters:		check                                *
;*	Output parameters:	check, arrow (L/R only)              *
;*	Local variables:		ABC, temp                            *
;*                                                           *
;*************************************************************

checkbox:
	ABC	=	BoxA									
	
checkbox2:
	row = 1														;start with A
	col = 0
	gosub locate

	temp = check & BoxA
	if temp = BoxA then
		char = checked
	else
		char = unchecked
	endif
	gosub sendChr											;print box
	char = "A"
	gosub sendChr	

	col = 7														;now do B
	gosub locate
	temp = check & BoxB
	if temp = BoxB then
		char = checked
	else
		char = unchecked
	endif
	gosub sendChr
	char = "B"
	gosub sendChr	

	col = 14													;then do C
	gosub locate
	temp = check & BoxC
	if temp = BoxC then
		char = checked
	else
		char = unchecked
	endif
	gosub sendChr	
		char = "C"
	gosub sendChr		

	select case ABC										;position the cursor
		case BoxA
			cmd = line2
		case BoxB
			cmd = line2+7
		case BoxC
			cmd = line2+14
	end select

	gosub sendCmd											;and blink it
	cmd = block
	gosub sendCmd			

	gosub getKey											;read the arrow keys
	select case arrow
		case up, down
			check = check xor ABC					;toggle the select bit
		case left
			ABC = ABC << 1								;move to previous
		case right
			ABC = ABC >> 1								;move to next
	end select

	if arrow = up then goto checkbox2
	if arrow = down then goto checkbox2
	if ABC > BoxA then goto checkbox3	;change of menu
	if ABC < BoxC then goto checkbox3	;ditto
goto checkbox2
		
checkbox3:
	cmd = curOff											;turn off the cursor
	gosub sendCmd
return			

;*************************************************************
;*                                                           *
;*	Wait for and fetch arrow keystroke                       *
;*	Input parameters:		none                                 *
;*	Output parameters:	arrow                                *
;*	Local variables:		temp                                 *
;*                                                           *
;*************************************************************
	
getKey:
	temp = not buttons				;read switch port
  temp = temp >> 2					;shift into lowest part of byte
  temp = temp & %00001111		;mask off junk above
	
  select case temp					;covert to simple form
  	case 1
			arrow = up
		case 2
			arrow = down
		case 4
			arrow = left
		case 8
			arrow = right
		else										;more than one or
			arrow = 0							;no buttons pressed
	end select	
	
	if arrow = 0 then					;loop until pressed
		goto getKey	
	endif	
	
	pause mSec50							;pause for debounce

	do												;wait for open switches
		temp = not buttons			;read switch port
	  temp = temp >> 2				;shift into lowest part of byte
	  temp = temp & %00011111	;mask off junk above
	loop while temp != 0  		
return	
	
;*************************************************************
;*                                                           *
;*	Send Value to AY Register                                *
;*	Input parameters:		register, value                      *
;*	Output parameters:	none                                 *
;*	Local variables:		none                                 *
;*                                                           *
;*************************************************************

store:
  control = inactive					;clear BC1, BDIR
  control = latchAddr					;latch address of register
  bus = register								
  control = inactive
  bus = value									;get value and
  pulsout BDIR,AYPulse				;store it
return	

;*************************************************************
;*                                                           *
;*	Fetch Value from AY Register                             *
;*	Input parameters:		register                             *
;*	Output parameters:	value                                *
;*	Local variables:		none                                 *
;*                                                           *
;*************************************************************

fetch:
  control = inactive					;clear BC1, BDIR
  control = latchAddr					;latch address of register
  bus = register								
  control = inactive
  
  control = readReg						;read the register
  dirsB = %00000000						;make bus input
  value = bus
  dirsB = %11111111						;restore outputs
  control = inactive

return	

;*************************************************************
;*                                                           *
;*	Print A, B or C Labels                                   *
;*	Input parameters:		register, value                      *
;*	Output parameters:	none                                 *
;*	Local variables:		temp                                 *
;*                                                           *
;*************************************************************

printA:
	chrSave = "A"
	goto printLetter

printB:
	chrSave = "B"
	goto printLetter
	
printC:
	chrSave = "C"
	
printLetter:
	row = 0
	col = 15
	gosub locate
	char = chrSave
	gosub sendChr
return