[LMH]microcode rom

[Michael Larson]

Thanks, found it. Any idea on what the format is? If the EII used a 64  
bit 16k microcoded RAM then the size would be about 128k... it probably  
has some of the dispatch table stuff in there also.

As a point of history I took my first AI class on an Explorer II  
machine, although my focus was on a BSEE and couldn't wait to be done  
with the class, I have re-discovered Lisp in the past few months and  
this looks like a fun project.

The idea I had for the microcode was to parse the microcode  
instructions into a C (or asm) switch statement based on the decode of  
the instruction for each case statement, this would provide a nice fall  
back to emulate the dispatch table used by the lisp compiler. On newer  
processors it would be better just to churn through the assembled code  
and avoid as much decode (branches) as possible.

It would be nice to boot my G5 to a VM that could access all 8 GBytes  
physical or 64 TeraBytes virtual.

Cheers,

Mike

On Dec 30, 2003, at 9:54 AM, Nyef wrote:

> On Tue, Dec 30, 2003 at 09:27:03AM -0800, Michael Larson wrote:
>> I am not sure how active this list is as the last results were posted
>> 2001, but here goes.
>
> That sounds suspicious. I can well believe that the last CVS checkin on
> E3 was in 2001, but almost everything else has been worked on at some
> point this year.
>
> Checking the mailing list archives shows that we last had activity on
> the 10th of December, this year.
>
> Things actually have been kindof slow recently, though. Maybe the new
> year will get us somwhere...
>
>> Is there a copy of the Explorer II microcode available? I would like  
>> to
>> do some experimenting with run time compiling the microcode to a jump
>> table for execution on the G4.
>
> I believe we may have an E2 microload around somewhere. What we don't
> have for the E2 are the boot proms or the CPU NuBus config ROM.
>
> http://www.unlambda.com/lispm/explorer-source/explorer-lispm-sources/ 
> ubin/
> should have the file you are looking for, specifically exp2_ucode.mcr.
>
> I must say that from what little I've done with the PPC, it feels like
> it would be a -wonderful- target for a microcode interpreter. Or a
> dynarec setup for the microcode. The fact that it actually supports
> most of the complex action of the BYTE instruction natively is great.
>
>> Thanks,
>>
>> Mike Larson
>
> --Alastair Bridgewater