All right, I learned that:

(a) moving Java code and Java VM functionality into microcode is
     how it should be done on a CISC processor.

(b) the VAX 8600 makes microcode hacks particularly easy since it
     always loads the microcode from diskette during boot

(c) the VAX 11/750 also has an easy access for microcode hacks
     as used by NetBSD.

Question remains: what about other platforms? Espcially the
6000 series? I think the only way to update microcode would be
through the EEPROM update process. This could actually be
convenient, because it doesn't require reloading at every
power-up time. OTOH it could also be dangerous because what
happens if you load a bad EEPROM hack? Will you ever be able
to fix this again (in other words, is the KA64A etc. EEPROM
load process 100% fail-safe?).

Next question is: would every generation of VAX require a
completely custom microcode hack or is there a level of
microcode compatibility?

(d) Another issue that was discussed is Java requiring IEEE floating
point while the VAX does not quite comply... however, I wonder
how important is the binary FP compatibility? You probably only
need to hack the serialization interface for the float and double
built-in data type. There shouldn't be any need for binary
compatibility once the FPs live in memory. I would try to avoid
replacing VAX floating point, because that would come with a
pretty good performance penalty. You coulnd't use the VAXvector
stuff, your native interface would be awkward, etc.

Finally I learned that (e) chicks dig guys who can hack VAX
microcode (Dave McGuire) ... if I were a teenager, I would
learn VAX microcode now, but, I do know for a fact that this
is false advice. Don't forget to live a life :-)

regards
-Gunther



-- 
Gunther Schadow, M.D., Ph.D.                    gschadow@regenstrief.org
Medical Information Scientist      Regenstrief Institute for Health Care
Adjunct Assistant Professor        Indiana University School of Medicine
tel:1(317)630-7960                         http://aurora.regenstrief.org