On Mon, 2003-12-01 at 14:06, Ethan Dicks wrote: OK. I'm trying to figure out how to cable some equipment up and I had (erroneously) thought that the cabling between POSIBUS and NEGIBUS was the same. For reference I'm trying to hook up the following: PDP-8/I DM01 TC01 FPP12 I can make the 8/I either POSIBUS or NEGIBUS (but right now it's NEGIBUS). The FPP12 can go either way too. The DM01 and TC01 are definitely NEGIBUS (but I guess I'll have to actually verify that too). I'll have to actually see what cables everything wants/needs because the documentation for the TC01 seems to indicate 5 cables between the devices (M904's?). -- TTFN - Guy

On Mon, Dec 01, 2003 at 08:27:18PM -0800, Guy Sotomayor wrote: ISTR 7 cables between my -8/i and the first DF-32 in the rack. 11 doesn't sound outrageous to propagate *all* possible negibus signals I have only seen such cables come already attached to devices. I think you may have to fabricate them. Now... what you can do is to make a *double-sided* board and design it to be universal. You'll just be using 50% of its potential. -ethan -- Ethan Dicks, A-130-S Current South Pole Weather at 02-Dec-2003 08:10 Z South Pole Station PSC 468 Box 400 Temp -21.1 F (-29.5 C) Windchill -49.6 F (-45.3 C) APO AP 96598 Wind 9.30 kts Grid 078 Barometer 699 mb (9916.2 ft) Ethan.Dicks(a)amanda.spole.gov http://penguincentral.com/penguincentral.html

connector the even Checked the schematics, and what they show is a set of universal paddles leading to a little board with all the cross-connects in it. A lot of the cross-connects look suspiciously like M904/W011 wiring :-). The paddles also have space for a second 40-pin connector (which is not actually installed on my DF32 emulator paddles), so you could daisy-chain them if you wanted to. Vince

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

If you used a spare header to daisy chain using ribbon cables, you'd save up to 11 paddles per device, and only need 55 total. The way that works is that instead of using a pair of paddles for "bus in" and "bus out", you'd use one paddle, but it would have an "input" ribbon and an "output" ribbon. It is my understanding that the devices essentially wire a pairs of sockets 1-1 for the "bus in" and "bus out" connectors. (I have quoted "input" and "output" because it is a bus, and there is no real difference between them.) Of course, that won't look quite right to whoever compares your hardware to the manuals :-). Vince

Guy Sotomayor wrote: Would shielded ribbon cable do the same thing? I suspect it might be a bit less expensive.