On 1/11/19 3:41 PM, allison via cctalk wrote: > On 01/11/2019 02:55 PM, Bill Gunshannon via cctalk wrote: >> On 1/11/19 2:25 PM, Allison Parent via cctalk wrote: >>> Most Probable cause is interrupt grant is broken. For most microspheres >>> backplanes the first three slots are different than remaining. >> Yes, that's true. But the problem doesn't occur until the 5th slot. >> And a quick look at the C-D edges of the board shows that the BUS >> Grant lines are jumpered. So the 2 A-B slots should pass the grants >> just fine. I saw no mention about these not working in A-B/A-B >> backplanes. The only mention the docs make at all is that the >> only lines used on C-D slots is power. >> >> bill >> > That is generally true... however there were more than a few odd backplanes > including a few that were wired for Core and some design to suit a > different > memory and incompatible (smoke releasing!). Others are unique as the RL11 > two board set require a CD backplane slot pair (will not work if ABAB).
Not only that, it will kill the RL11. > > You need to look at the backplane and find out what one it is. > > I have a few boxes I got without a backplane at all and as a result they > have > what I find was most useful and very non standard. > > The CSR complaint is because if you talk to the board and don't get a > int vector > or can't set a working one (floating) the CSR is broke. This is a > behavior that > is much different from unibus. It also happens if an expected CSR is > non standard > for nominal drivers. An example is my 11/73 as it has 2 RQDX3 so one > has to be > at a new and unusual CSR same for the second DLV11J serial. Some memory > (parity or ECC) also have CSRs and if they interupt and the drive is not > there > I've heard havoc ensues (of all my memory on hand none have that). > > Irs a side effect of the Q bus starting in the 70s (LSI-11) and > continuing with > some evolution though the 90s (11/83 and 11/9x). > At this point I am going with your comment about bus grant. I don't know why but that seems to be the likely culprit. More to follow if I get this working. bill
