PDP 11/03

jwsmobile jws at jwsss.com
Mon Nov 9 19:06:24 CST 2015

On 11/9/2015 4:42 PM, jwsmobile wrote:
> 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.
The M9400 seems to possibly be the Floppy boot and some other logic.  
I've not pulled either of these since getting the system to examine them.

A post by Tony Duell some years back states that the M7940-YA may have 
both a current loop and RS232 drivers for the port.  That would make 
things complicated, but might explain the puzzling extra bit in the Dec 
module description about extra wires.

I may see if Megan Gentry is still around with any notes on what was put 
in the Dec modules guide on World.std.com

>>      > 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.)
> Yep
>>      >> 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
> Thanks
> Jim

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