RL02 version of UNIX6?

Noel Chiappa jnc at mercury.lcs.mit.edu
Wed Feb 1 15:50:15 CST 2017

    > William Degnan

    > It "boots" to the ! prompt at least there's that.

Yeah, but not much has to be working for that to happen! :-)

    > I am unsure if one can put an M7891 into a slot that has no NPG jumper
    > installed

Yes, you can - but having a slot with no NPG jumper, and either i) no board
in in it at all, or ii) a non-DMA-speaking board in it, will prevent any DMA
device _further down the bus_ from working.

    > I would have to check, or whether I can put this card into a DD11-B

No. It needs a MUD slot (UNIBUS in connectors A-B, essentially; more here:


although other places have info about this too). (I'm not exactly sure how
the A/B connectors on DD11-B slots 2 and 3 are wired, it's something wierd,
look at the DD11-B prints for more.)
    > or a slot without the NPG installed.

The NPG jumper is IRRELEVANT to everything except DMA devices (in that slot,
and downstream).

    > Typing *anything* kills the system.

Well, technically speaking, that's not entirely accurate - clearly, from the
below typing "r" doesn't crash the machine. I gather you meant 'typing
"{anything}<CR>" crashes the machine'. Hmm.

    > When I type say rlunix or foobar or whatever and hit enter, the prompt
    > returns to the next line and the CPU stops. The system crashes,
    > unresponsive, requiring restart from the front panel.

That sounds like the bootstrap isn't running properly.

Oh, I remember an issue I had with the boostrap when first trying to bring up
Unix in Ersatz-11 - does your -11/40 have the EIS board? Is the EIS working?
If not, the bootstrap won't run - it uses the MUL instruction. (MUL is not in
the base set on an -11/40, it's an option.)

If that's not it, we'll have to debug the bootstrap... Should't be too hard,
test versions can be loaded directly into memory with GUI-11, we don't have to
write them to disk. You've got a (hopefully good) disk to have the bootstrap
ponder over...


More information about the cctech mailing list