[Coco] SCSISYS question

[Gene Heskett]

On Friday 19 September 2008, Tim Fadden wrote:
>I was following the SCSISYS thread, and had a few questions of my own.
>
>I have scsisys1.1 on my level2 system with a disto 4in1 with no
>multipak, and two quantum 105s drives. I built this around 1992 or so,
>maby later. I used it activly untill about 1998.  In the last month or
>so, I have pulled it out of mothballs an tuned up the hardware and got
>it all working again.  I now see there is a 2.2 version of scsisys.  Is
>this available any where?  Is Matt still around an perhaps be able to
>provide/sell a copy?  I don't really have any problems with this one.
>Just thought the commercial version may have some improvements worth
>getting.

No idea what Matt is doing today.

>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.

>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.

>Tim Fadden
>
>P.S. I do have the abbreviated set from
>rtsi/os9_6809/cocoos9.zip/drivers or wherever exactley they are, but I
>might need some help compiling and getting them to work.  Its been a
>while!   :-)
>
>
>
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-- 
Cheers, Gene
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