31 Aug
2006
31 Aug
'06
11:29 a.m.
At 2:55 PM -0700 8/30/06, Don North wrote:
Brad Parker wrote:
For those that don't have this handy and to fully document the
discussion, here is the text of item 36 from the 1983-84 Architecture
Handbook:
CLR and SXT do just a DATO sequence for the last bus cycle: 23/24, J-11.
CLR and SXT do DATIP-DATO sequence for the last bus cycle: all others.
John
An obscure unibus & pdp-11 question:
Does "clr" always do a DATIP (i.e. read-modify-write) on all 11's?
According to the PDP-11 CPU handbooks, the J-11 based designs did
the extra optimization so a CLR does not do the read, only the write
cycle (see item #36 in later handbooks).