PDA ramblings...

Matt Rogers matt at matt.rogers.name
Thu Feb 6 18:23:51 PST 2003

On Thursday 06 February 2003 08:11 pm, you wrote:
> Well, I've spent two hours when I should have been sleeping tonight to
> reverse engineer more of the bootloader...
> I have a partial map of the call structure of the bootloader, and where
> its data is (attached below for the curious).

hehe, i'm curious :)

> I know where all the code and data is up to 0x71c8, which is about half
> of the total amount of code in the bootloader.
> hopefully most of the rest will be data, but I doubt it.

Here's hoping!

> I have identified what code I can, except that I got tired, so much is
> labeled 'code' and 'data'. Eventually, all of the code will be traced so
> I can see the call sequence.
> I can identify a lot of the code by the locations in memory that it
> accesses, as I have a document with the memory map of a PXA250
> microporcessor. this will make identifying MMU, CF, SD, IR, and other IO
> code easy, although it wont help me see WHAT the code is up to...

Ok, I think i know what SD and IR stand for. Enlighten those of us who don't 
know what MMU or CF stand for. (We're not worthy!!!!! :) )

> Tomorrow, I will see if I can finish at least the map, and hopefully the
> call-tree as well.

I wish I had that much time on my hands. Stupid school stuff :(

> All I can say is... THANK GOD that 3/4 of the 256KB is image data! this
> is a LONG slow plod.

Image data? what kind of image data? (hehe, i'm thinking logos and stupid shit 
like that, even though that's probably not at all what it is)

> Im going to be pda-less for a couple of days, since it needs to return
> to toshiba for minor repairs (audio recording 'clicks' and the wireless
> switch is broken, bah!). when I get it back, hopefully I will have some
> code to try on it ;-)

Only a couple of days? Now that's what I call service! Nice! (Let's hope it 
doesn't turn into weeks)

> Oh, and I have found a local company that will do SMT rework of mBGA
> chips... Im going to buy a PXA255 (faster CPU, basically a PXA250
> without the bugs in its cache) and get it fitted. I will then have the
> fastest XScale PDA in the world (and the difference is NOT small - over
> 4X the memory bandwidth!) ;-)

faster is good :)

> I am getting the 'extended temperature' version of the chip too, on the
> grounds that it will be a 'tougher' sample, and might withstand
> overclocking... I wonder if I can get the PDA to run at 600MHz... that
> would be TOTALLY cool. (I think that may cause all the other timings
> (serial, CF, etc.) to run 33% fast also though, so that may not be a
> good idea...).
That would be cool.  :)  

> Well, My head is fscked now, and I still have to clean the kitchen,
> before bed. night night...
[snip of bootloader map]

Interesting.  Makes me want to brush up on my assembly again. (and to think 
that my assembly class (the only time i've actually programmed in assembly) 
was only two years ago). 

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