Path: blue.weeg.uiowa.edu!news.uiowa.edu!uunet!bloom-beacon.mit.edu!senator-bedfellow.mit.edu!pbauer From: pbauer@ATHENA.MIT.EDU (Paul H Bauer) Newsgroups: comp.sys.apple2 Subject: SCSI Connector Pin Outs Date: 20 Jul 1994 12:43:36 GMT Organization: Massachusetts Institute of Technology Lines: 68 Message-ID: <30j65o$jem@senator-bedfellow.MIT.EDU> NNTP-Posting-Host: bolognese.mit.edu Keywords: SCSI Connector Hard Dive This should probably find its way into the FAQ but hopefully it will be of help to those people having problems with Hard drives "dissappearing" when one or more devices are disconnected from their SCSI chain. Remember that Apple Cards generally do not provide SCSI terminator power so one or more devices on the chain must provide this power to see anything on the chain. Here are the pin-outs for the various connectors: SCSI pinouts: 25 pin ident 50 ide 50 SCSI RIBBON GODrive 1 REQ 48 49 36 2 MSG 42 46 30 3 I/O 50 50 33 4 RST 40 45 29 5 ACK 38 44 28 6 BSY 36 43 26 7 GND 37 19 8 DB0 2 26 6 9 GND 39 20 10 DB3 8 29 12 11 DB5 12 31 16 12 DB6 14 32 18 13 DB7 16 33 20 14 GND 1,3,5 1,2,3 15 C/D 46 48 34 16 GND 7,9,11 4,5,6 17 ATN 32 41 25 18 GND 13,15,17 7,8,9 19 SEL 44 47 32 20 DBP 18 34 22 21 DB1 4 27 8 22 DB2 6 28 10 23 DB4 10 30 14 24 GND 45,47,49 23,24,25 25 TPWR 26 38 24 IDE 50 pin connector "into drive" 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49 50 PIN SCSI Ribbon connector 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 ____________________________________________________________________________ \ o o o o o o o o o o o o o o o o o o o o o o o o o / \o o o o o o o o o o o o o o o o o o o o o o o o o/ ------------------------------------------------------------------------- 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 pbauer@mit.edu