Re: Zip disk on Apple SCSI

[Rubywand <rubywand@swbell.net>]

David Empson writes ...
> 
> Louis Cornelio <cornelio@crl2.crl.com> wrote:
> 
> > The iomega zip drive is set to SCSI ID5 with the termination switch on.
> > I am lucky to have any SCSI card! :) How exactly would the apple hi-speed
> > need to be "modified"?
> 

> .... Without termination power you will almost > always get unreliable > communication over the bus.
> 
> The RamFast does provide termination power, and either Apple card can be
> modified to do so by adding a diode in the correct location ....
> 
> .... I'm not all that happy with
> the idea of the SCSI card supplying it, because it can cause the card to
> draw more current from the +5V rail than the rated maximum for ALL cards
> together. ....

     If you can get a hard drive on the end of the chain to supply
termination power, then, sure, this is the way to go. Otherwise, you are
probably stuck with getting your juice from the computer.

     My RamFAST feeds termination power to both a Zip drive and CD-ROM
drive-- the Zip drive's termination is usually left ON whether or not
it's at the end of the chain. This setup performs well on a 4MB GS which
also powers a Focus drive, Stereo card, and 10/64 ZipGSx.

     A single Zip drive is a fairly light load. There should be no
problem with using an Apple Hi-Speed SCSI card after doing the
termination power mod described by Dan Brown and Harold Hislop in the
hispeed.gif pic on Ground at ...

ftp://ground.isca.uiowa.edu/2/apple2/Docs/ .


Rubywand