[LispM-Hackers] Microcode...

[Paul Fuqua]

    Date: Fri, 12 Apr 2002 14:59:54 -0500 (CDT)
    From: Daniel Seagraves <dseagrav@sakura.lunar-tokyo.net>
    
    Is the stuff in ubin/*.mcr microcode?

Yes.
    
    If so, what's the format?

Several sections, for instructions, dispatch-table memory, tag-table
memory, and a couple other sections I forget.  I dug up my old
LOAD-MCR-FILE code the other day -- I want to do a little software
archeology and disassemble and annotate the microcode -- but it's at
home.  No symbol tables, alas.
    
    Third, the two load bands you guys have; Could they be used to cold-boot
    a real machine from absolutely nothing?  (say, a machine with zeroed disk
    drives?)

Once upon a time, that's what one did:  put a load band and a microcode
band on a disk, flag them as "default" with a magic tool, and the boot
process would load them up and go.  (In my first weeks as a microcoder,
I would often build microcodes that didn't work;  in that case I had to
lug the disk brick to another lab where I could hook it to a handy CADR
and move the "default" flag to something that worked, then lug it back.)

I think that would still work, but the "modern" way was to first boot a
special microcode that would offer a menu of bands to boot, including
load bands, microcodes, and diagnostics.  Or was it two-stage:  initial
boot and self-test, which loaded the menu boot?  Fuzzy memory.

                              pf