21 Jun
2007
21 Jun
'07
11:44 a.m.
writing code to emulate the lisp machine microcode was
not that hard,
but getting it *exactly* right turned out to be difficult, [...]
Heh. I have a MicroVAX-II simulator that's sort of on hold. I had
similar issues; there are some undocumented (as far as I can tell)
aspects of the hardware which the ROM POST code depends on. (For
example, the CPU has an instruction stream prefetch buffer, and the
hardware can run out of the prefetch buffer even though the stuff there
is not what would be fetched from those addresses now, under some
circumstances. I had to give the simulator a prefetch buffer. :-/)
Now, I'm stuck dealing with some serial line timing issues....
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