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         Mitey Mo AUTOMODEM Specs
                   
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           Pinout Functions
           ----------------

Pin Function Computer IN/OUT
--- -------- -------- ------

B   CB1      RXD      IN
C   PB0      RXD      IN
D   PB1      A/O      OUT
E   PB2      SQT      OUT
F   PB3      RI       IN
H   PB4      DCD      IN
J   PB5      HOOK     OUT
M   CB2      TXD      OUT

Note: See PROGRAMMER'S REFERENCE GUIDE
      pages 331-332, 355, 360-361  for
      information  on  accessing  pins
      from BASIC or M/L.

           Pin Descriptions
           ----------------

RXD - RECEIVED DATA - This is the
    received data and is a modem
    output signal into theC64. It
    comes on CB1 and PB0 which are
    tied together in the modem.

A/O - ANSWER/ORIGINATE - This is an
    input signal to the modem from the
    C64. It comes in on PB1. the
    ANSWER MODE is selected by a
    low(0v) signaland the ORIGINATE
    MODE by a high(+5v) signal.

ST - SQUELCH TONE SIGNAL - When this
    line is high(+5v),there will be no
    transmitted tone out of the modem.
    During normal operation, this line
    should be low(0v). The purpose of
    this line is to squelch the tone
    during dialing sequence and during
    the two(2) second FCC hold-off
    period. It may also be used to
    squelch the tone for voice
    communications or other signaling.
    This signal comes out on PB2. This
    is an input signal to the modem.

RI - RING INDICATOR - This signal is a
    modem output signal on PB3. It is
    normally high(+5v). When the phone
    rings, it goes low with each cycle
    of the ring frequency. So for each
    ring, it will go low about 20
    times. It is used for AUTO-ANSWER
    MODE to know when the phone is
    ringing. When using this mode, it
    is best not to allow the computer
    to answer until about one and a
    half rings have gone through. This
    would be about thirty ring cycles.
    Rings occur at about one second
    intervals and unless a count
    thirty is established in two
    seconds, it is possible to get
    transient noise to trigger the
    ring circuit.

DCD - CARRIER DETECT - This is an
    output signal to the modem on PB4.
    This signal goes low(0v) 250ms
    after a carrier has been detected.
    A program should be set up so that
    no information is transferred
    unless this signal is present
    which means use the squelch.
      
HOOK - HOOK/DIAL SIGNAL - This is an
    input signal to the modem on PB5.
    When this signal goes low (0v),
    the phone line goes OFF HOOK. This
    line should go low to answer a
    call or to originate a call. This
    line is also used for pulse
    dialing. The ratio for pulse
    dialing should be 39ms to 61ms
    with 39ms being OFF HOOK. Between
    digits, there should be a wait of
    800ms. Remember ZERO is ten
    pulses.

TDX - TRANSMIT DATA - This is an input
    signal to the modem on CB2. This
    is the data fom the C64 to be
    transmitted out on the phone line.

These specifications courtesy of:

Gary Farmaner
628 Trafford Cr.
Oakville, Ontario
L6L 3T5
TEL (416) 827-8564

The programmer of PRO-TERM 64 V1.3

     This file  was  made  by  Darrell
Grainger  on  February  24,  1985 from
note by Gary Farmaner,  and  formatted
into a bulletin by Geoffrey Welsh.