Noel Chiappa jnc at mercury.lcs.mit.edu
Wed Jun 1 12:24:43 CDT 2016

    > From: Rod Smallwood

    > if you try to get it to boot it says no controller to every device
    > except DD and that says no drive

Hmm, I wonder if that's a clue. Ah, probably not: 'DD' means 'TU58', which is
interfaced through a standard serial line (DL11 clone), and the standard
device location for the TU58's serial line is 776500, which is the standard
address for the first serial line, and since the 11/94 has a bunch of serial
lines, the code probably thinks there's a TU58 there. But there isn't...

    > I cant get it to go into ODT to look at the registers.

If you look in the "PDP-11/84 System Technical and Reference Manual"
(EK-1184E-TM-001), available here:


Section 3.7 lists several ways to get into ODT. In addition to those, if you
look at Section 3.2.2, it allows you to configure the machine to fall into
ODT on power-on (section B gives details).

    > From: Henk Gooijen

    > The first 4 (5?) slots are QBUS

Technically, PMI, which is more-or-less QBUS on the left (A/B) side (modulo
not having grants, unless the appropriate backplane jumpers are set to send
grants to those slots), and it uses the standard CD interconnect (as in Q/CD
backplanes) on the right (C/D) side to carry PMI.

    > The RX211 must have the NPR/NPG open. Check the documention which DIP
    > switch must be set in the correct position. However, not sure if that
    > would cause the RX211 to be "invisible".

Right; DMA would not work, but normal master/slave UNIBUS read/write cycles
to the device registers should still work.

    > Can you check the RX211 in another UNIBUS system? See whether its CSR
    > responds.

Another good test would be to plug a known working UNIBUS card into the
11/94, and check if the CPU can 'see' it.

    > Also, check the configuration of the RX211. It might be set to a
    > different CSR ...



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