11/44 memory question
ak6dn at mindspring.com
Sun Nov 5 00:24:34 CST 2006
Zane H. Healy wrote:
> At 10:04 PM -0600 11/4/06, Jay West wrote:
>> It would appear that the slots designated "MEMORY" in the 11/44
>> (slots 9-12 in the *system* backplane) are actually "Extended Unibus"
>> slots. My reading is that these slots allow 22 bits of memory
>> addressing instead of 18.
>> So, of they are still "unibus" slots, does that mean that if there is
>> one board in slot 9, that slots 10-12 should have grant continuity
>> cards (G727)?
>> If they are unibus slots I would certainly think so, but they are
>> designated for memory only... and I can't find any reference to using
>> grant cards there for non-populated memory slots.
> I'm pretty sure you don't need grant cards, but my /44 is buried. The
> /44 can use up to 4MB, and IIRC, I only have 1MB. I needed the grant
> cards, but in slots where options had been removed.
> It's just like you don't need any kind of grant card in the CPU slots
> if you don't have the extended CPU options installed.
You don't need grant cards in the 11/44 backplane slots 9-12 since they
are not SPC slots. The AB portion of the slot is 'extended unibus' EUB
(adds address lines 18-21 for 22b addressing) but the CDEF sections are
not SPC slots. If they are not used for memory they should be left
empty; you can put a grant card (either type) in these unused slots --
it won't hurt anything, but it is not necessary. Empty memory slots
cannot be used for UNIBUS SPC modules either.
Only the last two quad slots 13,14 CDEF in the 11/44 backplane are SPC
and these require G727A/G7273 grant cards depending on whether the NPG
wire has been removed.
The modules have the grant propagation lines intact because they could
*theoretically* go in a MUD (modified unibus, 18b, with associated SPC
section) or an EUB (22b) slot. These modules work in the 11/44
(dedicated EUB memory) slots or the 11/24 (MUD/EUB/SPC slots) which need
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