Re: regular Apple SCSI card question

[Wayne Stewart <waynes@intergate.bc.ca>]

Generally speaking if the drive does require termination, then you'll 
most likely run into read/write errors. If it requires termination 
power then the computer probably won't even recognise the hard drive. 
This can be solved by either modifying the SCSI card or attaching 
another HD to the end of the chain that doesn't require termination 
power. I'd hesitate to guarantee anything but when I was new to 
computers I must have had every mixture of no termination, double 
termination and termination power when I wasn't supposed to, and 
I've yet to damage a  HD. Or maybe I'm just lucky.  

I did connect a 40mb hard drive from a IIcx to an Apple SCSI card a 
while back. Quite a while actually. I don't recall needing 
termination power with that drive. I do  recall though that there 
are a set of three plug-in terminating resistors on the HD. They're 
near the rear of the HD on the circuit board. They have 8 inline 
pins each. You may want to remove them and use an external 
terminator. Although as long as that's the only device attached 
they could be left in. If so then don't attach an external terminator.

They do make DB25 pass-through terminators though I don't recall 
ever seeing one used on an Apple II. What's much more common is a 
centronics 50m pass-through terminator. Some drives do like this type 
of terminator but usually you just use one terminator on the last 
device in the SCSI chain.
I'll probably get flamed a bit for saying this but. After the Ramfast.
if I'm not using a removable media drive and actually changing the 
media while the computer is on, then I prefer the Rev C over the 
HI-Speed SCSI. Also, I have trouble telling the two cards apart speed 
wise without a stopwatch. If you're looking for another card I'd 
suggest a Ramfast. In every case it'll beat the Hi-speed by a huge 
margin. The one advantage the Hi-Speed has is with drives that 
require the SCSI card to have a SCSI id. The Ramfast will not work 
with those drives. 


      Wayne


Jason Whorton wrote:
> 
> Hello.  I just received an Apple II SCSI card today.  It is the regular
> kind, not the High Speed version.  I also received a new Apple SCSI System
> cable (25 - 50) and new terminator.  Until my HD80SC arrives in the mail, I
> would like to use a 40MB HD from a Mac IIcx.  I have an IBM external SCSI
> case that the drive will fit in, as well as provides a place for the
> terminator to go on the end of the SCSI chain.  In the SCSI System Cable
> manual, it says that the Apple II SCSI card does not provide termination
> power.  Will I damage the card if I use it without termination power?  Can I
> find a terminator that is DB-25 on both sides?  Does anyone have any tips on
> what I should do?