Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!usc!rpi!zaphod.mps.ohio-state.edu!mips!ptimtc!nntp-server.caltech.edu!toddpw From: toddpw@nntp-server.caltech.edu (Todd P. Whitesel) Newsgroups: comp.sys.apple2 Subject: Re: scsi cable frustrations Message-ID: <1991Jun11.231202.6172@nntp-server.caltech.edu> Date: 11 Jun 91 23:12:02 GMT References: Organization: California Institute of Technology, Pasadena Lines: 23 sk2f+@andrew.cmu.edu (Seth D. Kadesh) writes: >Just double checking with you hardware gurus out there: from the 50 >pin centronics (female) to the 50 pin header connector (to the drive), >all pins go straight through (pin 1 to pin 1, ... pin 50 to pin 50)? Yep. If you get it backwards, don't panic -- you won't be able to see the drive from the computer but it won't fry anything. >Why are there 50 pins in the SCSI cable, if there's only 25 pins >coming out of the RamFast? The other 25 pins are either all ground or or are complemented (actually opposite voltage, but only higher end SCSI systems do it) versions of the first 25. Apple chose the 25 pin connector because it was small and much easier to mount on the mac motherboards than the 50 pin centronics. Ya know, the RAMfast does have holes on it for a 50 pin header with the exact same pinout as the one on the drive. Don't know if you want an exposed ribbon cable though. (They put it there for internal drive hookups.) Todd Whitesel toddpw @ tybalt.caltech.edu