Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: Notesfiles $Revision: 1.7.0.8 $; site uiucuxc Path: utzoo!watmath!clyde!burl!ulysses!mhuxr!mhuxn!ihnp4!inuxc!pur-ee!uiucdcs!uiucuxc!german From: german@uiucuxc.Uiuc.ARPA Newsgroups: net.micro.pc Subject: Re: IBM AT Serial Line Pinouts Message-ID: <21900070@uiucuxc> Date: Sat, 24-Aug-85 11:45:00 EDT Article-I.D.: uiucuxc.21900070 Posted: Sat Aug 24 11:45:00 1985 Date-Received: Mon, 26-Aug-85 01:18:28 EDT References: <2077@ukma.UUCP> Lines: 39 Nf-ID: #R:ukma.UUCP:-207700:uiucuxc:21900070:000:1507 Nf-From: uiucuxc.Uiuc.ARPA!german Aug 24 10:45:00 1985 It has been awhile since this information was last posted to the net so here it goes: The IBM PC AT Serial/Parallel Adapter has a 9-pin D shell type connector which is configured as follows: Pin Signal Name (DCE) RS-232C Pin (DCE) ----- -------------------- ------------------- 1 Carrier Detect 8 (CD) 2 Received Data 3 (RD) 3 Transmitted Date 2 (TD) 4 Data Terminal Ready 20 (DTR) 5 Signal Ground 7 (SG) 6 Data Set Ready 6 (DSR) 7 Request To Send 4 (RTS) 8 Clear To Send 5 (CTS) 9 Ring Indicate 22 (RI) The above is for attachment to Data Communications Equipment such as a modem. To attach to another terminal (DTE) device the following signal lines must be changed: Pin Signal Name (DCE) RS-232C Pin (DTE) ----- -------------------- ------------------- 2 Recieved Data 2 (TD) (RD & TD Swapped) 3 Transmitted Data 3 (RD) 4 Data Terminal Ready 6 (DSR) (DTR & DSR Swapped) 6 Data Set Ready 20 (DTR) / 7 Request To Send 4 (CTS) \ (Pins jumpered together at \ 8 Clear To Send 5 (RTS) / each end only in pairs. Pin 7 to 8, 4 to 5. Not needed for Full-Duplex operation.) This information may be obtained from the IBM Technical Reference, Options and Adapters Mannual, Volume 2 after installing update pages which are actually provided in the Technical Reference, Personal Computer AT Mannual. This means you need the AT tech ref to get the specification if you haven't already obtained one.