[LMH]Nevermore

[Robert Swindells]

Alastair Bridgewater wrote:
>On Wed, May 19, 2004 at 10:27:37PM +0100, Robert Swindells wrote:
>> 
>> Are there any plans to put nevermore into CVS ?

>Not really, no. I still don't like CVS.

>> I have made a start on adding Explorer-II support to it along with
>> some code to parse microcode files.

>Oho. On the theory that because all of the other hardware is the same it 
>should just be a matter of writing a new CPU emulator? One of the main 
>reasons I was concentrating on Raven was that we're closer to having a 
>full romset for Raven than we are for Hummingbird (either the ExpII or 
>the MX), but I'm certainly open to the idea of emulating both.

I took a look at it because I know that I have matching MX load and
microcode bands. The other reason was that I don't know the format
of the ExpI microload.

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.

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 ?

>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.

>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.

>Have you been concentrating on parsing the microload and a disassembler, 
>or do you have some instruction emulation as well?

Both.

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.

>And would you mind sending me a patch? I may as well at least put 
>together another release this weekend or something.

Ok, I'll put it together later.

>And, of course, the inevitable documentation and ROM request: Does 
>anyone have manual part number 2248114-0001 (32-Bit Lisp Microprocessor 
>Specification), ROM dumps from an Explorer II, or a working Explorer II 
>system? (I suspect that we may need to write our own microload to read 
>the IROM and EPROM, and we should certainly be able to write a Lisp 
>function to dump a NuBus declaration ROM...)

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.

I'll send you a copy of the dump.

Robert