3COM CORPORATION

VARMODEM 1200

Modem Type             Data (synchronous/asynchronous)
Maximum Data Rate      1200bps
Data Bus               8-bit ISA
Data Modulation        Bell 103A/212A
Protocol
                       ITU-T V.21, V.22

[Image]

                                CONNECTIONS

         Purpose           Location            Purpose           Location

  Line out                    CN1       Volume                     R1

  Line in                     CN2

      MULTI-LINE INSTALLATION

  Setting                J1

  » Single modem         Off

  Multi-line             On

  TRANSMISSION FORMAT

  Setting        J2

  » 10-bit      Off

  11-bit         On

          RESET

  Setting        J14

  » Enabled      Off

  Disabled       N/A

  FACTORY CONFIGURED SETTINGS

     Jumper         Setting

       J3              On

                  BASE I/O ADDRESS SELECTION

        Port                 J10                  J11

    COM1: (3F8h)       Pins 2 & 3 closed          Off

    COM2: (2F8h)       Pins 2 & 3 closed          On

    COM3: (3E8h)       Pins 1 & 2 closed          Off

    COM4: (2E8h)       Pins 1 & 2 closed          ON

           INTERRUPT SELECTION

         IRQ                 J12

          3           Pins 2 & 3 closed

          4           Pins 1 & 2 closed

                                AUTO ANSWER

  Setting                                            SW1/1

  » Off                                   Modem answers on first ring

  On                                  Modem does not answer on first ring

           CARRIER DETECT

  Setting               SW1/2

  » Off               CD normal

  On               CD forced high

                                PBX MODE

  Setting                                          SW1/3

  » Off                              Normal dial up line equalization

  On                                           PBX operation

              DTR SIGNAL

  Setting                SW1/4

  » Off                DTR normal

  On                DTR forced high