[Coco] SCSISYS question

[Tim Fadden]

Gene Heskett wrote:
>
>
>   
>> As to your thread, I have everything in a pc case, so the cable is less
>> than 2 ft.  It was split all the way.  I had no terminators installed.
>> Having trouble with /h1 after reviving the coco, I ended up making a
>> cable as you describe with all 50 wires except at the controller. Wasn't
>> the problem, but I ended up with a better cable! ha ha ha   the
>> connectors from the drive assy to the disk circuit board were corroded,
>> and after cleaning up all the drive cables I got it working again.
>>
>> Term power should only supplied by one device on the chain.  with 18in
>> cables no term power probably works.
>>
>>     
> If you sacrifice enough virgins.  True scsi is an open collector bus, and must 
> have pullups in the form of terminations on each physical end of the cable.  
> They try to match the cable impedance, absorbing the echos.  The echo is an 
> interchangeable term with vswr in the radio/tv business, and the less vswr 
> the better.
>
>   
Ha Ha Ha,  I am not real up on the technical specifications only 
speaking from 20 years of working with
scsi systems as a support engineer for Sun Microsystems.  What is 
correct/spec, and what you can get by
with are not always the same. :-)

>> Any hoo, any info you could provide as to getting scsisys2.2 would be
>> appreciated.
>>     
>
> I think the scsi driver now in Nitros9-3.2.8 is probably its equal if not 
> better than 2.2.  The advantage of 2.2 was supposedly enhanced speed, but 
> even the original 1.1 could do a megaread in 13 seconds, where theoretical is 
> 11 at the coco's clock speed.  scsisys-2.2 to a Maxtor 7120s and myram to a 2 
> meg disto kit can both do it in 11 seconds so there wasn't a huge difference.
>
>   
I will look into this,  up to now, I have not seen much for Disto 4in1 
controllers with no multipak. And not
being intimate with the code, I wouldn't  know just what to tweek to 
make them work!


Thanks for the reply.

Tim Fadden