PDP-8 NEGIBUS Cables

From: Guy Sotomayor <ggs_at_shiresoft.com>
Date: Tue Dec 2 10:27:59 2003

On Tue, 2003-12-02 at 07:27, vrs wrote:
> > On Tue, Dec 02, 2003 at 02:10:36AM -0800, vrs wrote:
> > > At 11*2=22 boards/device, you are even
> > > talking quantities that make sense to send out to a board fabricator.

> It looks about a buck cheaper for small quantities of single sided.
> Checking online, it looks like $13.21 vs $14.46 for 1 week delivery. 5
> weeks is $9.40 each for the two-sided boards, all qty 30.
>
> 30 bare-bones one-sided cards can be had in 5 weeks for $7.81 each, no
> solder mask or silk-screen.
> 30 bare-bones two-sided cards can be had in 5 weeks for $8.62 each, no
> solder mask or silk-screen.
>
> That's just one vendor, of course, but it is the one with the steepest
> quantity discount I know. Those boards are around $4 each qty 100, and
> $2.50 each, qty 500 :-). As the quantity goes up, the difference in price
> also goes down. If you are using 20-odd per device, it might be possible to
> use 100 :-).

Since I need something like 44 cables (8/i, DM01, TC01, FPP12, DF32)
100 isn't really too many. Now all I have to do is find the coax ribbon
cable...

>
> Of course, single sided cards are not as generic, so you might as well make
> them W011 clones and use narrower headers and ribbon, for additional cost
> savings :-).
>
> > > BTW: Any market for DF32 emulators out there? I like mine, but I
> wondered
> > > if there was demand to get more made?
> >
> > I'd love one, but I might have to convert my negibus -8/i to posibus to
> > use it. I suppose I could throw one on my 12K 8/L. I've always wanted
> > to have disk on it. How much harder would it be to make an RF08
> > emulator? :-)
>
> I don't think it would be too hard, but then I didn't do the design work on
> the DF32 emulation :-). Basically, it is like some of the talk on another
> thread -- an NVRAM chip, some counters and gates for data break, and a bus
> interface card that collects up all the Posibus signals. It emulates all 8
> possible drives (and exports write-protect switches for each one :-)). Last
> I heard, there was a diagnostic function unimplemented that keeps it from
> being 100% software compatible. I should recheck the RevB schematic to see
> if that has been addressed yet. Replaces a whole rack with a 1U device :-).
> I just have to get my 8L working well enough to use it :-).
>
> It also occurred to me that one could turn the generic boards into M904/W011
> clones by using the pads for the second header to install the ground jumpers
> needed. That would give a very clean look, but would also use more paddle
> cards than ribbon cable daisy chaining.
>
> Vince
-- 
TTFN - Guy
Received on Tue Dec 02 2003 - 10:27:59 GMT

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