31 Mar
2008
31 Mar
'08
5:25 p.m.
I'd have to look up the RL11 to know if it could
be used in a 22 bit
machine, but if so, it'd be 17777404 and 17777400.
Nope. No Unibus peripherals support 22-bit NPR addressing, since Unibus
has only 18 address bits. On a Unibus system with 22-bit addressing
support (11/70, 11/84, 11/94) the Unibus Map has to be used to translate
the 18-bit Unibus addresses into 22-bit memory addresses.
The RH70 supports direct (unmapped) 22-bit addressing, but it isn't
actually a Unibus device. For NPR, it transfers data via the cache
subsystem, rather than over Unibus.
Some Qbus devices support 22-bit NPR. If memory serves,
the RLV21 has 22-bit addressing while the RLV11 does not.