8 Jan
2009
8 Jan
'09
11:17 a.m.
Alas having got my 11/05 working, its developed a problem. Bit 5 on the
lower 8KW of memory (it has two sets of G110/G231/H214 8KW cores) has
failed and is always set to 0
Does this indicate a failure in the X/Y drivers?
Given that it's only kalf of the memory, I think it's safe to say it's a
problem with the memroy board set and not the CPU or backplane.
But I don't think it#'s the X/Y drivers which are the addressing
circuits. More likely to be a problem with the snese/inhibit circuitry.
I've not looked at hte printset for _years_, but I suspect you have 16
indentical sense/inibit cirucuits (one for each bit) whivh gives you
something to compare signals with.
How is the base address of core memory set? Are there
jumpers on the
boards or is it position in the backplane that determines its location?
DEC never used 'geogrphical addressing' (depending on slot position) on
the Unibus (or for that matter Omnibus or Qbus). The address will be set
by jumpers on the PCB (although I don't know which of the PCBs in the
memroy board set contains the addressing jumpers).
-tony