Wanted: DEC cables BC08J

[vrs]

From: "Paul Koning" <pkoning at equallogic.com>
>  Ethan> Sorry... never even _seen_ those.  You could probably make a
>  Ethan> set from a prototyping card and some ribbon cable, though.
>
> That may not work... you want controlled impedance cable.  I looked
> for the spec, but didn't see it; it may be the same as Unibus cable,
> which is documented in the Unibus handbook.
>
> Conventional ribbon cable is not controlled impedance, though there
> exists higher end cable that is.

It is pretty easy to find ribbon that is spec'd for impedance.  It would say
it is more a matter of avoiding the low-end ribbon, these days.

The older Negibus/Posibus cables are spec'd for 93 ohm coax.  I suspect
you'd do OK with 100 ohm ribbon.

I think a tougher issue with ribbon is how to keep the cables from sitting
on top of each other and having a mess of crosstalk.  The older coax doesn't
have that problem :-).  I am also building a few Negibus/Posibus cables out
of CAT5e, in an attempt to mitigate that problem.

    Vince