Another DCJ11 oddity
jnc at mercury.lcs.mit.edu
Tue Jul 10 05:01:52 CDT 2018
So, if one looks up the Cache Control Register in, say, the KDJ11-A
(EK-KDJ1A-UG-002), one sees (in section 220.127.116.11) that there are _three_ ways
to disable the cache: bits 2, 3 ('force miss'), and 9 ('bypass cache').
Looking at the DCJ11 manual (EK-DCJ11-UG-PRE) doesn't provide any additional
(The 9 bit one is slightly different than the other two, because it causes
cache contents to be invalidated as the code runs, whereas the other two
What is going on here, does anyone know? I'm _guessing_ that this is for
compatability with the -11/70, where the cache is divided in two ('two-way set
associative'), and either half can be disabled separately (using the 2 and
3 bits in its CCR).
I suppose only someone who worked on the DCJ11 would know; but I have no idea
how to track down such a person.
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