[LMH]Nevermore

[Robert Swindells]

Alastair Bridgewater wrote:
>On Thu, May 20, 2004 at 11:34:09PM +0100, Robert Swindells wrote:
>> 
>> Alastair Bridgewater wrote:
>> >On Thu, May 20, 2004 at 05:31:12PM +0100, Robert Swindells wrote:
>> >> 
>> >> 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.
>> 
>> I don't seem to have that function in dise1uc.lisp.

>Oop. Yeah, that's in my current version. I tried to send you a tarball 
>of my WIP directory, but I guess that didn't go through.

When did you send it ? My outgoing email was being sent with an incorrect
reply address for a few days.

>> >Heh. Is it just using the micronet interface to indicate the presence of 
>> >a microload and having the STBM take it from there?
>> 
>> I think it must be.
>> 
>> See what you think when you get the tarball.

>The first thing that comes to mind is "Dear lord this is nasty". The 
>most horribly K&R C I've seen in ages, half of the system in Pascal as 
>well, it -is- a NuPI simulator, and they depend absolutely on the system 
>not only being 24-bit capable (not true of the later machines) but also 
>running in 24-bit mode (if memory serves, not true of System 7). It 
>might be possible to get an MX running on a more recent machine 
>(possibly even a powermac), but it'd require basically rewriting all of 
>the MacOS-side code.

It is pretty ugly. There are warnings in the documentation about not
using the network from MacOS and the MX at the same time, so it would
be worth rewriting it anyway.

>> >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?
>> 
>> My MX won't boot, so I'm just poking at it from the Macintosh side.
>> 
>> The ExpII processor document states that the NuBus config ROM contains
>> the STBM. I was just guessing that the MX was the same, but couldn't
>> see anything that looked meaningful.

>Mmm... That config ROM image doesn't look right at all. It looks to be 
>short a byte, and shouldn't it be longer if you're doing word-wise dumps 
>and the bytelanes value is #xE1? (at least, I assume that's the 
>bytelanes value...)

I'll take a look at how I'm mapping it later. I probably stopped one
byte too soon.

I can easily dump out the whole 16MB if I need to, I have written a
NetBSD driver for it.

>What would be really nice is if one of the nice TI people would stumble 
>across a copy of the 256-word IROM code from the hummingbird chip. 
>Otherwise we may have to write a custom microload to extract the code 
>once we have access to a working system... I suppose it doesn't really 
>matter for now, we can probably fake something up to get it working in 
>the meantime...

It seemed fairly easy to unpick the ExpII microload, I would suggest
just setting the micro PC to the correct address and letting it go.

It made sense for you to use the ExpI roms to debug Nevermore, but
256 words doesn't really seem a big enough sample to help much with
an ExpII variant.

Robert