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From: russotto@eng.umd.edu (Matthew T. Russotto)
Newsgroups: comp.sys.mac.hardware,comp.sys.mac.misc
Subject: Re: Question on Removable HD
Message-ID: <1991Jan6.192235.936@eng.umd.edu>
Date: 6 Jan 91 19:22:35 GMT
References: <1991Jan2.232147.4576@agate.berkeley.edu> <962@chem.ucsd.EDU> <5901@testeng1.misemi>
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Organization: College of Engineering, Maryversity of Uniland, College Park
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In article <5901@testeng1.misemi> stanfiel@testeng1.UUCP () writes:
>In article <962@chem.ucsd.EDU> rich@sdchemf (Richard Kanner) writes:
>> I asked APS about this and they said that the SCSI terminator
>>on the SyQuest needed to be powered up inorder to work.
>
>This is true of all SCSI terminators. The SCSI spec. includes a signal
>called TERMPWR. This signal can be supplied by the host or the device.
>There are diodes used to prevent reverse power feed. Unfortunately,
>Apple, for some reason, omit this signal from their (non-standard)
>SCSI connector. I'm not sure why this is, because there is a spare pin
>on the connector (P25). 

Actually, pin 25 is used for TERMPWR on all Macs above the Plus, according to
the hardware reference (this hardware reference also has pinouts for the ROM
SIMM in the Mac II, so you might want to take it with a few grains of salt..)

--
Matthew T. Russotto	russotto@eng.umd.edu	russotto@wam.umd.edu
     .sig under construction, like the rest of this campus.