Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!uwm.edu!ogicse!cvedc!mcspdx!adphdw20!dtb
From: dtb@adpplz.UUCP (Tom Beach)
Newsgroups: comp.periphs.scsi
Subject: Re: A ribbon cable for scsi?
Summary: Actually you're both right...
Message-ID: <685@adphdw20.UUCP>
Date: 16 Apr 91 14:47:14 GMT
References: <1991Apr15.131049.4752@mailer.cc.fsu.edu>
Distribution: usa
Organization: ADP Dealer Services R&D, Portland, OR
Lines: 18

In article <1991Apr15.131049.4752@mailer.cc.fsu.edu>, sloderb@mailer.cc.fsu.edu (Mike Sloderbeck) writes:
> My dealer just sent me a 10' cable (scsi (centronics) 50pin each end)
> made out of ** ribbon cable **.  Surely, lines must be twisted for a scsi
> cable of this length?  Who's right, me or the dealer?
> 
YES! The SCSI spec allows either. It's an interesting point whether the 
twisted pairs are better than the shorter wires you get with a standard
ribbon. Whether you'll have any problems with 10' of this stuff depends
on how fast you're running, how good your terminations are, whether you're
running synchronous or asynchronous, ... . I have run systems with 
multiple devices on 10' of ribbon cable with no problems. These systems
are based on the Motorola 88000 RISC processor set and have and
Interphase high performance Dual SCSI controller. It's a high performance
system. I do have good active terminators. I've also used the "twist
and flex" twisted pair ribbon cables. They work well also and are 
A LOT easier to manage in a crowded peripherals bay!!

Tom