On Sun, May 15, 2016 01:17, Don North wrote: > On 5/14/2016 2:41 PM, Noel Chiappa wrote: >> > From Ed Groenenberg >> >> > - insert both CPU cards, KY11-LB card & bootstrap card, 5 full >> grant >> > cards, DL11-W and bus terminator card. >> > ... >> > - cntrl + boot shows register dump at printer. >> > ... >> > All looks ok >> >> I'm surprised the bootstrap ran OK with no memory at all in the machine. >> I >> vaguely STR that I had a machine that would not work like that, but >> maybe I'm >> wrong. (DEC bootstaps tend to do things like set the NXM vector, in low >> memory, so they can size memory; and when it gets the NXM (since there >> is no >> memory) from trying to touch the NXM vector, and tries to push the old >> PS and >> PC to service _that_, and gets _another_ NXM, that 'double bus fault' >> often >> causes many -11 processors to do a cheap suit) > > If the bootstrap card is an M9312 with the standard console PROM, it does > NOT > require any > memory to be present/accessible to get to the ODT prompt that prints out > the > registers and > waits for a command. Only until you execute a device bootstrap command > with > 'diagnostics > enabled' (the default) does the memory sizing/test/diagnostic code get > exectuted. > > Listing: http://ak6dn.dyndns.org/PDP-11/M9312/23-248F1/23-248F1.lst > > So the system working to this level with no memory present is normal. > >> >> > power down machine, add memory (M7981, 128KW) >> >> What's an M7981? Did you mean an M7891 MS11-L? >> >> > - power up machine -> run light is on, does not get cleared by >> > cntrl + halt. >> >> This is where a UA11 would really help. I had similar issues with an >> -11/04, >> and the UA11 was a huge help in figuring out what's going on. One glance >> and >> you can see if a bus line is wedged, or something. > > Agreed, a bus probe would really be helpful in further debug. Given that > the > system does not > even get back to the ODT prompt (which would not yet access memory) > indicates > that logic > on the memory card is hanging the bus. Could be a bad bus driver interface > chip > (8641, etc). >
I'll hook up the bus analyzer and see it there is something to see. >> > - power down & replace memory with grand card -> run light is >> off. >> >> Well, that's good sign - the memory card didn't fry anything, at >> least... >> >> > - tried a 2nd memory card (M8722, 128KW) >> >> Ooops. The MS11-M needs +/-12V, which is _not_ standard in most >> machines/backplanes). The EUB in the 11/24 and 11/44 (which this card is >> intended for) does have it. The really bad part is that those same pins >> usually carry +/-15V in most MUD backplanes. So hopefully you didn't fry >> it. >> It does have standard UNIBUS as well as EUB, but there's a jumper, IIRC. > > Bad idea to put this card in an 11/34. As indicated the +12V VDD rail on > the > memory chips > is wired directly to the UNIBUS +15V line in the 11/34 (which can be set > to +12V > in the 11/44). > So you placed +15V (or more likely up to +15.5V or so) onto the memory > chip VDD > lines. > Some 16K chips had a 15V max spec on this pin, others only 13.2V. So it is > possible you > toasted so memory chips, or not, depending on manufacturer and their > sensitivity > to OV. I'll label the card as 'possible not working' for a test later in a proper machine. > In any event, DO NOT use this card again in the 11/34. It is not > compatible with > the backplane. > >> > So what could be the problem here? The bus works without the >> memory >> >> Two possibilities off the top of my head. i) The first memory card is >> bad (or >> configured incorrectly), or.. ii) The M7891 uses +/-15V as well as +5V? >> So >> maybe one of the other voltages is not so good? But you said the console >> worked, and I think that uses other voltages (at least, in EIA mode - >> not >> sure about 20mA, I never touch the stuff). >> >> Noel >> > > Ed -- Ik email, dus ik besta. BTC : 1J5fajt8ptyZ2V1YURj3YJZhe5j3fJVSHN LTC : LP2WuEmYPbpWUBqMFGJfdm7pdHEW7fKvDz
