Re: A Question Of Termination

[salfter@chakotay.ncc74656.org (Scott Alfter)]

In article <88npoq$nfu$1@nnrp1.deja.com>,  <mystix1210@my-deja.com> wrote:
>OK, by my understanding all SCSI devices on a chain must be terminated,
>both at the beginning and at the end of the chain. Pretty simple right,
>just stick a terminator block on the last device. That works in theory
>if the SCSI card is self terminating. But what if it isn't. I've been
>having odd problems with my setup and am wondering if the RamFAST isn't
>terminated. If this is the case, then I'd have to set termination on the
>first device and last device right?

The RamFAST is terminated...look for three resistor packs soldered between
the 26-pin and 50-pin ribbon connectors (assuming you have a rev. C
RamFAST...I've never seen a rev. D and don't know its parts arrangement).

One possible problem might be that the drive doesn't supply termination
power.  I replaced the two 40-meg drives I was using (a Conner CP340 and a
Quantum ProDrive 40S) with a single 320-meg drive (an IBM 0661-370).  The
Conner and Quantum drives supply termination power, but the IBM doesn't (the
IBM doesn't even have a place to plug in resistor packs, so off-drive
termination is required even if it's the only device).  If none of the
devices in your SCSI chain supply termination power, the RamFAST can be set
to supply it (don't remember which switch controls it).  Using this option
exceeds the power budget for an Apple II expansion slot, though, so only use
it if you must.  (I also have a Zip drive and a Panasonic 4x CD-ROM on my
chain, and of those, the CD-ROM drive supplies termination power.)

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