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Teddy Boom
k kudos Received
Premium Member
join:2007-01-29
Toronto, ON

1 recommendation

Teddy Boom to mlord

Premium Member

to mlord

Re: Upgrading Firmware on Thompson DCM475

said by mlord:

So I'm pretty close to hook-up time. Once I get the new 'duino going, the first task is to rip the 02.08 firmware a few times via different sequences, and do binary compares to judge the reliability of the communications. Then try erasing and reprogramming just the 02.08 firmware, and do readback/verify again.

If that all works, I'll get hold of the 02.16 modem and snatch a copy of the latest firmware from it.

Install the USBJTAG software and take a look at how cable modem flash is organized on other modems, it will help a lot. If you need a flash dump from a modem, I can pass that along..

In particular, what you'll find is that some of the firmware will be human readable. Try searching for "DCM" and "docsis" in a hex editor. If you've read the firmware properly you should find strings like that. When my friend read a DCM425 chip for me, the bytes always came out flipped:
If I load 425-1.bin into USBJTAG and then inspect image0 I see the
string as follows:
CD4M525-.2803.-1118032S-.Sib.n

Flip the bits and I get:
DCM425-52.08.31-110823-SS.bin.

So maybe it is all just pairwise swapped?!?!
So I googled around a bit and found HEX Workshop, which conveniently has a byte swap feature. Not long after that I had a working ST52.08.31 image.
»www.hexworkshop.com/

Unfortunately no Sayal in Ottawa:
»www.sayal.com/zinc/zinc_ ··· ctus.asp
But there must be an electronics supply place.. Not sure about test clips, but they aren't that obscure, so the odds can't be too bad.

TSI Gabe
Router of Packets
Premium Member
join:2007-01-03
Gatineau, QC

TSI Gabe

Premium Member

That's called Endianness

»en.wikipedia.org/wiki/Endianness

x86 are little endian

While in this case is likely MIPS based which is usually big endian.

Teddy Boom
k kudos Received
Premium Member
join:2007-01-29
Toronto, ON

Teddy Boom

Premium Member

said by TSI Gabe:

That's called Endianness

Thanks! I've heard of little endian and big endian before, and I probably even dealt with the ideas a little 15 years ago, but I sure didn't make the connection.

I mentioned that I'm an analog guy right?