" " "======================================" " Commodore 1650 AUTOMODEM Specs" "======================================" " " "Pin ID ABV Description" "--- ---- ---- ------------------------" " " " " " A - GND Ground " " B FL2 RXD Received Data " " C PB0 RXD Received Data " " D PB1 RTS Request To Send " " E PB2 DTR Data Terminal Ready " " F PB3 RI Ring Indicator " " H PB4 DCD Data Carrier Detect " " J PB5 HOOK Dial / Hang Up " " K PB6 CTS Clear To Send " " L PB7 DSR Data Set Ready " " M PA2 TXD Transmitted Data " " N - GND Ground " " " "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 the C64. It" "comes on CB1 and PB0 which are tied" "together in 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. " " " "TXD - 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."