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- APPENDIX F -- RBBS-PC And The AT's RS-232 Cable F-1
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- APPENDIX F -- RBBS-PC And The AT's RS-232 Cable
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- The RS-232 serial connector is different for the AT than the PC or XT. The
- AT uses a connector called a DB-9, which is a 9 pin connector. An
- alternative to buying the AT serial cable from IBM, ($65-$80), is to make
- your own. A ten-wire cable can be purchased from any local computer store
- for about $.80 per foot, and the DB-9 and RS-232 connectors with hoods can
- be purchased from Radio Shack. The total cost should be about $12.00. A
- modem hooked up to the AT will work fine with the 9 pins connected in all
- terminal functions, except for auto-answer applications such as RBBS-PC.
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- RBBS-PC requires pin 1 from the modem to be hooked up to the chassis ground
- on the AT or it can't answer the phone. There are two ways to hook up the
- ground wire on the computer end. The first way is to use a metal hood to
- cover the DB-9 connector. Wrap a bare wire that is attached to pin 1 of
- the RS-232 connector around the cable on the DB-9 end. When the metal hood
- is screwed down over the cable a connection will be made. When using a
- plastic DB-9 hood simply solder a wire from pin 1 on the RS-232 end to the
- metal body of the DB-9 connector. Since documentation is scarce for the
- AT, following figure lists the necessary pin connections for those wanting
- to make their own AT RS-232 cable.
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- DB-9 RS-230
- (Computer (Modem Description
- End) End)
- ========= ======= ==================
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- GROUND -------- 1 -------- Protective Ground
- 1 -------- 8 -------- Data Carrier Detect
- 2 -------- 3 -------- Receive Data
- 3 -------- 2 -------- Transmit Data
- 4 ------- 20 -------- Data Terminal Ready
- 5 -------- 7 -------- Signal Ground
- 6 -------- 6 -------- Data Set Ready
- 7 -------- 4 -------- Request to Send
- 8 -------- 5 -------- Clear to Send
- 9 ------- 22 -------- Ring Indicator
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