[Coco] Multipak redesign/replacement

[Mark Marlette]

I agree and would also like to add.....

In the CC3 the address bus is unbuffered, a disaster in the works if you add any capacitance to the lines.

>From a CoCo SCSI point, most did not implement the SCSI bus properly from a bus drive current, termination or full SCSI ID support perspective.

My experimentation in to a CC3 bus extension, left me at a reliability issue. Twisting, grounding, termination, shielding, etc....Wanna do it right and have 100% reliability, differential T/Rs....Which from a signal stand point = lots of parts! Real test is to xfer a hard drive and verify that no bit was lost. Hard to do on an extension.......YMMV.

Mark Marlette 
http://www.cloud9tech.com 
mark at cloud9tech.com
________________________________
From: RETRO Innovations <go4retro at go4retro.com>
To: CoCoList for Color Computer Enthusiasts <coco at maltedmedia.com> 
Sent: Tuesday, February 24, 2015 10:23 PM
Subject: Re: [Coco] Multipak redesign/replacement


On 2/24/2015 9:33 PM, Gene Heskett wrote:
>
>
> I can't speak to his product offering, but I am not prepared to create
> something that causes people issues.  I appreciate that certain lengths
> or specific brands of flat cable might do OK on 1.77MHz signals, but
> such cable is not designed for such speeds and should not be used for
> such speeds.
>
> Jim
> Au contaire;
>
> Transmission line class 101 is in session:
<snip>
While I appreciate the trip down to my EE class memories, you're 
responding to a specific use case with general information.

You should read the above as:

...such cable is not designed for such speeds [in the configuration Bob 
Rosen used] and should not be used...

I understand SCSI, but the SCSI flat cable spec puts a ground on every 
other line, and uses terminators as you note.  Neither are present on 
Bob's cable, to my knowledge.  If they are, my apologies.




Jim

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