[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