[LMH]Nevermore

[nyef@sc.am]

On Thu, May 20, 2004 at 05:31:12PM +0100, Robert Swindells wrote:
> 
> I started by trying to parse the microload, I then realized that it
> wouldn't fit into the 56 bit wide arrays. Once I had started modifying
> them I thought I might as well start on the microengine and
> disassembler.

Mmm... I suppose it wouldn't hurt to at least change the cached 
microinstruction storage to be 64 bits wide globally...

> I saw in an old message that you had worked out the ExpI ROM format,
> have you had any thoughts on the likely format of an ExpI microload ?

Ages back. See dise1uc.lisp, disassemble-mcr-partition for some of the 
details. I also posted a partially-commented disassembly of the STBM 
code to my webspace a while back ( http://www.dridus.com/~nyef/lispm/ ), 
which has the code to start a microload running on the machine.

> >Starting a microload without having the STBM code will be... 
> >interesting. Particularly if you start by loading the primitive.
> 
> The source to the Macintosh loader program is supplied with the
> microExplorer tree. It doesn't seem to be doing very much to start
> the board up.

Heh. Is it just using the micronet interface to indicate the presence of 
a microload and having the STBM take it from there?

> >I can think of a couple things I'd want to change if we're going to 
> >support Hummingbird in the same codebase. NuBus handling, for starters.
> >Breaking the CPU emulation out into a separate package from everything 
> >else as well... We might also want to look for a better name. Poe never 
> >wrote about a Hummingbird that said 'Nevermore'. ^_-
> 
> I have broken the ExpII versions of things out into their own files.

Right, but there are a few things that should be common to both that are 
in files with 'raven' in the name.

> I have only really done the bits that have moved around slightly
> within the microword. I have added handling of immediate a-mem
> values to the microengine, but not to the disassembler yet.

Oh, neat. A-Immediates look like they'd make a good improvement over the 
A-CONSTANT stuff from the Raven microloads. One question I have, though, 
is if they sign or zero extend...

> I have had a go at reading the ROM in my microExplorer.
> 
> What I can't tell is whether the diagnostic microload ought to be
> mapped into the NuBus address space or whether this is part of the
> reason for the board not working.

There's a specific diagnostic for the MX, right? Are you writing a 
replacement set of interface routines, or are you using the 'correct' 
ones?

> I'll send you a copy of the dump.

Cool, thanks.

> Robert

--Alastair