BC11A paddle boards

[Ethan Dicks]

On Wed, Jan 27, 2016 at 10:06 AM, tony duell <ard at p850ug1.demon.co.uk> wrote:
> DEC (also?) made a board that brought the Unibus out on 3 40-way
> cahles.

I don't know that I've seen that exact one, but it sounds like
something they would have done.

> I have removed that from my 11/730 as I just want a single-cabinet system,
> but of course have kept all of it.



> Didn't we have a thread on this a few months back?

Perhaps, but I don't remember if it was related toGuy's paddle boards
or just general kicking around of "how do I get "new" BC11A cables?"

>> more cost-effective than 4x30?  Mostly, I'm curious about how much
>> 60-pin ends cost and the difference in cost between 2 lengths of
>
> Practically, I would not want to use 60 way connectors and cable. They are
> not as easy to get as the 40 way ones.

I just did some pricing and 60-way cable is a touch pricey.  Through
cable surplus vendors, I saw one quote of $1.33/ft and from the same
vendor, prices close to $0.30/ft for 28-34-way (you need twice as many
feet, of course, but it's still half the cost.  Not a big deal for one
10' run, but trying to cable up 4 RK05s, for example, it would start
to add up).  3x 40-way wouldn't be too bad, if designing from scratch
(I totally get the design goal of a simple double-sided paddle card to
simplify the construction of that - I'm not complaining about Guy's
design, just investigating costs for different methods.  For just one
pair of paddle cards and one set of cables, the differences aren't
going to be enough to matter.  Wanting/needing multiples for multiple
systems or drives might start to tip the balance).

> [I've never seen a 30 way IDC socket. 34 way are common of course.]

I'd have to check the paddle card with my DWBUA, but I'm pretty sure
the cables are 30-pin to 30-pin, not 30-pin to 34-pin (the VAXBI
backplane is studded in 30-pin keyed connector spots (6 per backplane
slot) and are the only way to get signals to/from BI options.  We made
a COMBOARD VAXBI (only sold a handful - too late in the game to
matter) and took two 30-pin cables out to our I/O bulkhead dual EIA
connector plate.  The DWBUA has 4x 30-pin cables to get Unibus from
the BI board to the paddle card in the DD11DK.  They certainly aren't
common.  I only mentioned them because I've seen it done.  3x40-way is
probably more sensible since 40-pin parts and cable were once
incredibly common.

-ethan