On Sat, May 14, 2016 23:41, 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)
Could that be done on later models? (i.e. 11/24 and up?) > > > power down machine, add memory (M7981, 128KW) > > What's an M7981? Did you mean an M7891 MS11-L? Yes, a typo, it is a M7891. > > > - 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. Ah, that reminds me, I have an original DEC Unibus analyzer, which is one of those small suitcase sized boxes and has a display for all bus signals. Stupid that I didn't think about that. > > > - 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. Ah, well it was not set for EBU mode, but ISTR that there is a jumper which selects for +12 or +15 volt. > > 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). Yes, both +5 and +15 is used and measure ok on the backplane. > > Noel > Ed -- Ik email, dus ik besta. BTC : 1J5fajt8ptyZ2V1YURj3YJZhe5j3fJVSHN LTC : LP2WuEmYPbpWUBqMFGJfdm7pdHEW7fKvDz
