PDP-8 NEGIBUS Cables

> 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 :-).

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 :-). wondered 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