On Mon, Jun 14, 2021 at 10:34 PM Tom Uban via cctalk <cctalk@classiccmp.org> wrote:
> On 6/14/21 3:39 PM, Noel Chiappa via cctalk wrote: > > > From: Tom Uban > > > > > it has the early version M7261E Control Logic & Microprogram board > and > > > the later version M7260 Data Paths board > > > > Ah, I'm glad someone found all that stuff I wrote up there useful. As > always, > > I _think_ I got it all transcribed correctly, but do be on the lookout > for > > errors! > I most certainly did - thank you for creating it! > > > it seems like an older/newer combination, but maybe that was > common. I > > > would not have guessed that the four possible combinations would > all > > > work together, but maybe they do? > > > > I honestly don't know. As far as I can tell, the DEC documentation > doesn't > > even _mention_ the two different board generations; perhaps a sign that > they > > are functionally interchangeable? (Although even the section on baud > rate, in > > both DEC-11-HKDBB-A-D and EK-KD11B-MM-001, 4.11, doesn't even mention the > > early board. So maybe the manual just ignores the earlier version > completely?) > > > > I don't have an /05 up and running at the moment, or I'd check all 4 and > see > > if they all work. > > > > > Presently, the machine sometimes runs relatively well and other > times > > > it does not. > > > > What are the failure symptoms? (It's almost certainly going to take a > 'scope > > to fix it; I expect you have one?) > I have KM11s, a scope, a logic analyzer, a unibone, shiresoft unibus > analyzer, etc. > No shortage of gear, just a shortage of time. > > I'd start by monitoring the CPU clock, and make sure it's running when > the > > failure happens. (Note that the front console is handled by the > microcode, so > > if the microcode isn't running, the machine will be totally dead. > > EK-KD11B-MM-001 has a good description of how that works.) > I think I checked the clock when I started this project a while back, but > I will > check it again. Unfortunately, I haven't figured out how to provoke two > states, > but it mostly picks the completely dysfunctional state, so I'll look at > the clock. > > > my initial messing with KM11 boards, reveals that I can step the > > > microcode with a KM11 in either the #1 or #2 position, but when two > > > KM11s are installed at the same time, they do not function properly > > > together. Is this expected or do I have an issue there too? > > > > Not sure. EK-KD11B-MM-001 (available at: > > > > http://www.bitsavers.org/pdf/dec/pdp11/1105/EK-KD11B-MM-001_Jan75.pdf > > > > and definitely something you need) says, at pg. 5-6 "KM11 switches have > the > > same function in slots KM-1 and KM-2", and on 5-7 "permits the user who > has > > only one KM11 to plug into either KM-1 or KM-2". > > > > So that _sounds_ like you should be able to plug two in together. The > first > > indicates that the switches, the only input to the KD11-B from the KM11, > are > > wired in parallel, and the only other thing on the KM11 are the lights, > > outputs. And why mention "user who has only one KM11", if having two is > no > > use because one can't use two at once? > I've read that doc, but did not come away with the impression that both > can be used at the same time or not. > Just to provide some real-world data, I used a pair of KM11's to debug my 11/05, see the picture here: http://yahozna.dyndns.org/scratch/1105-debug.jpg They worked fine. (These are clones, from Guy Sotomayor's kit.) I can verify tonight whether I have the earlier or later rev CPU set, if that helps. - Josh
