Path: ns-mx!hobbes.physics.uiowa.edu!zaphod.mps.ohio-state.edu!mips!mips!munnari.oz.au!comp.vuw.ac.nz!actrix!David.Empson From: David.Empson@bbs.actrix.gen.nz Newsgroups: comp.sys.apple2,from.socal.com Subject: Re: Connecting two //gs via Serial port Message-ID: <1992Apr18.031107.26265@actrix.gen.nz> Date: 18 Apr 92 03:11:07 GMT References: <1992Apr15.121814.757@ausom.oz.au> <1992Apr16.143707.15218@pro-palmtree.socal.com> Sender: David.Empson@actrix.gen.nz (David Empson) Organization: Actrix Information Exchange Lines: 50 Xref: ns-mx comp.sys.apple2:35113 In article <1992Apr16.143707.15218@pro-palmtree.socal.com> bkogawa@pro-palmtree.socal.com (Bryan Ogawa) writes: > I think you may need a special cable, and NOT an ImageWriter cable.. > > can someone who knows more about this comment about hooking up 2 IIgses > with an IWII cable (shouldn't you use a null modem cable?) An ImageWriter II cable _IS_ a null modem cable. All Mini-DIN-8 serial ports on Apple computers and peripherals have the same pinout, which means that only one type of cable is required (rather than having to worry about "straight through" or "null modem" cables). I tested my ImageWriter II cable with a continuity tester, and it is wired as follows: 1 HskO ------ 2 HskI 2 HskI ------ 1 HskO 3 TxD- ------ 5 RxD- 4 Gnd ------ 4 Gnd 5 RxD- ------ 3 TxD- 6 TxD+ ------ 8 RxD+ 7 DCD ------ 7 DCD 8 RxD+ ------ 6 TxD+ Shield ------ Shield The only oddity here is pin 7, which goes to the DCD input of the SCC on a IIgs, but isn't used on a Mac or ImageWriter II. Using this cable to connect two IIgs's will result in the DCD inputs being connected to each other, which shouldn't be a problem (as long as the DCD signal is ignored). I have used this cable to connect my two IIgs's together, and to do an XModem transfer at 2400 baud (for testing a BBS). I haven't tried anything higher, but there shouldn't be any problem - the GS can't distinguish it from a modem connection. The control panel settings: DCD handshake must be OFF, DTR/DSR should be ON and XON/XOFF is optional. If your communications software expects the DCD input to be doing something useful, there may be problems. This cable may not be the same as the "official" Apple cable, but as long as your cable swaps TxD+/RxD+, TxD-/RxD-, HskO/HskI and passes ground through, it should work OK. -- David Empson Internet: David.Empson@bbs.actrix.gen.nz EMPSON_D@kosmos.wcc.govt.nz Snail mail: P.O. Box 27-103, Wellington, New Zealand