OSI CA-14? CA-15V universal telephone interface logical interface determined from software

Contains 2 6821 PIA,  Tone generator, Tone decoder, Tape control,
input/output multiplexer for Tape/Aux/Phone/Votrax,  300baud modem


PIA#1  $F800
PortA
	Bit 0  out    votrax output to phone enable 01  tone gen output	05
	Bit 1  out    aux    output to phone enable 02  pulse gen output 06 ???
	Bit 2  out    modem  output to phone enable 04  disable output 07
	Bit 3  in
	Bit 4  in
	Bit 5  in
	Bit 6  in
	Bit 7  in	ring detect
	(DDRA = 0x07)

PortB  $F802
	Bit 0  out   1\ = offhook  0\ = onhook         1\
	Bit 1  out   0/            1/                  1/
	Bit 2  out   tape play control    0=on 1=off
	Bit 3  out   tape recoder control 0=on 1=off
	Bit 4  in
	Bit 5  out   failsafe toggle 0->1->0 disarms failsafe for some amount of time
	Bit 6  in    failsafe disconnect 0 indicates disconnect
	Bit 7  in    tone detected when set (DTMF or dial or busy etc.)
	(DDRB = 0x2F)

PIA#2  $F804
PortA
	Bit 0  in    DTMF tone decoder input bits?
	Bit 1  in    DTMF tone decoder input bits
	Bit 2  in    DTMF tone decoder input bits
	Bit 3  in    DTMF tone decoder input bits
	Bit 4  in
	Bit 5  out   1\
	Bit 6  out   1- = modem auto answer
	Bit 7  out   1/
	(DDRA = 0xE0)

CRA $F805
    Bit 7 CA1 active transition flag. 1= 0->1, 0= 1->0 (goes hi on transition, cleared by read of ctrl reg)
	used to detect tone/no tone transition ???


PortB  $F806  (DTMF output select) FF=off  when bit=0 - enable tone
	Bit 0  out 0=697Hz         D7="0"   DE="2"   ED="4"   BD="6"   DB="8"
	Bit 1  out 0=770Hz         EE="1"   BE="3"   DD="5"   EB="7"   BB="9"
	Bit 2  out 0=852Hz
	Bit 3  out 0=941Hz        DTMF keypad and frequency  lsb   
	Bit 4  out 0=1209Hz        1    2    3    A  - 697Hz  (E) 	
	Bit 5  out 0=1336Hz        4    5    6    B  - 770    (D) 	
	Bit 6  out 0=1477Hz        7    8    9    C  - 852    (B) 	
	Bit 7  out 0=1663Hz        *    0    #    D  - 941    (7) 	
       (DDRB = 0xFF)              1209 1336 1477 1663Hz          
                             (msb)(E)  (D)  (B)  (7?)                
					
	lower 4 bits select row tone, upper 4 bits select column tone for DTMF



F808(R)		modem status
	Bit 0   1 = recv ready
	Bit 1	1 = xmit busy
	Bit 2	1 = modem error
	Bit 3   1 = modem in use
	Bit 4
	Bit 5
	Bit 6
	Bit 7	1 = modem ready

F808(W)  modem control
         0x67 = turn off modem
         0x03
		 0x11 = enable modem

F809(R) modem data read
F809(W) modem data send

Initialize modem
Write F808 $43, wait 10*10ms, $03, wait 300*10ms, $11, wait 400*10 ms,
Read  F808 & 08 = 1 Modem in use

something at $CD00  (hi bit set = busy?) maybe Votrax?


Modem Auto answer, write 0xE0 to $F804 , initalize modem

2 PIA ports configuration
Set DDR->$F800=7, F802=2F, F804=E0, F806=FF


$F802 = 0E = hangup , wait until $F802 = 0x0E
$F802 = 0D = offhook

$F806 = DTMF generation $FF=off

$F804 = 0xE0 = auto answer
$F804 = 0x60, wait 500ms, 0x40 = reset modem? modem loopback?

$F808 0x08 = RING

Ring Detect
$F808 = 0x43, wait 40ms, F808=0x11
when $F800 & $80 = 1, ring detected 

Failsafe probe
//F802 bit $20 is failsafe bit, toggle to 1 then 0 to indicate running 
X=$F802; $F802=X | 0x20; $F802 = X & 0xDF;

Failsafe disconnect
$F800 & 0x40 = 0 indicates disconnect

Tape recorder On
X = $F802; $F802 = X & $F7

Tape recorder Off
//$F802 bit $08 is tape recorder control. 0=ON 1 = OFF
X = $F800; $F800 = X | 0x08

Tape Play On
$F800 = 3; X=$F802; $F802 = X & 0xFB

Tape Play Off
//$F802 bit $04 is tape play control. 0= on, 1 = off
$F800 = 7; X=$F802; $F802 = X | 4;

Dial tone detect
$F802 bit $80 = tone detected when set

Votrax to phone enable
$F800 = 1

Aux to Phone
$F800 = 2

Modem output enable
$F800 = 4

Disable output to phone 
$F800 = 7