PDP 11/03

jwsmobile jws at jwsss.com
Mon Nov 9 18:42:07 CST 2015

On 11/9/2015 1:48 PM, Noel Chiappa wrote:
>      > From: Jim Stephensn
>      >> "extra wires to bring out clock & .. 110/300 speed change"
>      > I am mainly asking if I want to hook up a terminal, can I get it going
>      > with TD, RD and GND (or 2 3 7 on a DB25), or do I need to loop back any
>      > of the other pins.
> Well, without knowing how those extra pins work, it's very hard to say. Given
> that _apparently_ one could change the baud rate externally (which means that
> there's something in the cable - or at its other end - to do baud rate
> selection), I'd _guess_ that a stock cable probably wouldn't work.
> If you find a set of 11/780 prints, that _might_ include the specialized
> cable for this beast, but short of that, you're talking signal trace/etc time.
The 9400-YE has the cables that formerly went to the 11-780.  I'm not 
sure what it does.  The line below that I clipped out,  about the 
M7940-YA is for the adjacent card, and has no cable, just the open blue 
one waiting for an IDE cable to the back for serial connections.
>      > I have several 4 port DLV boards, but want to go with this as a
>      > reference. I paid a bit too much for it because it was "working"
> Yes, but it doesn't have the cable!
> Trust me, swapping to a DLV11-J is a fully known, simple, approach - not like
> trying to work with a serial board with an unknown header pinout!
> And that 'working' was some decades back! Who knows what the situation is now!

>      > I don't want to screw it up by replacing cards.
> If all you do is replace the M7940 with an M8043 in the same slot, that
> shouldn't present a problem (make sure the M8043 is configured properly to be
> the console, though; it is, however, very well documented).
>      > I know even less about loading the backplane than I do about hooking up
>      > a serial cable.
The M7940 has no cables, is open.  I'm not sure if the M9400 needs to be 
pulled or not to run the system.
> That's OK, I have recently run both M7940's and M8043's in my QBUS systems
> here; they are a straight replacement (albeit using different cables - a
> 40-pin Berg/DuPont connector on the former, and 10-pin Berg/DuPont on
> the second one).
>      > I was hoping to get some idea whether the correct cable might be
>      > available from someone on the list first, and buy it, or better, find
>      > out how to spot them on ebay. I've had a lot of luck with the boards,
>      > but none with finding listings for cabling.
> Like I say, I expect the cable for the M7940-YA is a special item. As for
> cables on eBay - fuhgeddabahtit!
> Well, that's not quite true: seller 'conflandard' has some console cables for
> sale, but I think only DLV11-J/11-23+ type (they are the same cable,
> basically - the header pinout on the two cards is the same, the difference is
> that the stock 11/23+ cable allows baud rate selection on the back panel -
> but an 11/23+ _will_ work with a stock DLV11-J cable, provided the board is
> jumpered correctly).
> I've _never_ seen a DL11 type cable (with the 40-pin Berg/Du Pont connector)
> for sale on eBay - well, not EIA ones. I think someone had an 20mA one for
> sale, once.
>      > and trying the 4 port cards. Most of them came from the cheap scrap
>      > guy, so I don't know the state of them as well. I've seen some people
>      > found there were duds in the pile.
> _Most_ of the cards I bought from him worked (I haven't been able to try them
> all, e.g. I don't have a working UNIBUS machine yet). The one exception was a
> DLV11-J on which two of the four serial ports didn't work.
> Once you have a working machine/board set, it all becomes much easier, of
> course - you can swap boards around and see which ones are working. (If you'd
> like, you can send me the DLV11-J, and I'll either send you a known
> fully-good one, or test yours and send it back, along with the results. I've
> done this for other people here.)
>      >> I can supply both null-modem and non-null-modem cable diagrams (for
>      >> DB25 connectors, already worked out; I have made DB9 serial cables,
>      >> but not for direct connection to a DLV11, but could generate those
>      >> too).
>      > I'd love that
> OK, let me go unearth the cable diagrams - or I suppose I could just look
> at a cable, I have a couple of mostly-finished ones on the workbench at the
> moment! :-)
> 	Noel

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