[time-nuts] FE-5680A firmware dump

[Bob Camp]

Hi

I'd bet that there's some code in there and some data tables. Without
digging in, it's hard to say how big each is. We could easily find that
there's 24K of code in the MCS51 and a bunch of tables in the PSD813.

Bob

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Azelio Boriani
Sent: Friday, February 17, 2012 6:06 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] FE-5680A firmware dump

OK, then maybe there are ROM bank switching as the MCS51 can't execute
beyon the 64K limit. It can be very challenging to follow a code that jumps
between 64K ROM banks. Moreover the MCS51 has to address the external RAM
by massive pointer use (the famous MOVX @DPTR,A and MOVX A, at DPTR
instructions) beyond the 256byte internal easier to address RAM. Yes, you
need a good disassembler, aware of bank switching and massive pointer use.

On Fri, Feb 17, 2012 at 11:20 AM, Javier Herrero
<jherrero at hvsistemas.es>wrote:

> Don forget the PSD813 :) It provides 128KB Flash and 8KB RAM... so it can
> be a bit more complicated
>
> Regards,
>
> Javier
>
> El 17/02/2012 11:09, Azelio Boriani escribió:
>
>> In my opinion you don't need the power of an IDA-class disassembler to
>> process an 8051-like code. The MCS51 family processors have only 128 or
>> 256
>> bytes of RAM (and at most 64K ROM) and cannot host complex code.
>>
>> On Fri, Feb 17, 2012 at 10:27 AM, Elio Corbolante<eliocor at gmail.com>
>>  wrote:
>>
>>  From: Mike McCauley
>>>
>>>> I've been considering ripping the firmware from the mcu as well.  I've
>>>>>>
>>>>> not
>>>
>>>> got beyond the consideration stages, but i have all the equipment here
>>>>>>
>>>>> at
>>>
>>>> work. When you say that the read option is not available. is this
>>>>>>
>>>>> because
>>>
>>>> the chip has protection fuses enabled?
>>>>>>
>>>>> Id like to help with the disassembly if you can get the binary dump.
>>>>
>>>
>>> Don't worry: when I will be able to dump the firmware I will let it on
>>> the
>>> public domain.
>>> BTW, I have the opportunity to use the IDA disassembler (a friend of
mine
>>> is a licensed user) so I think the disassembly of the code will be
rather
>>> good.
>>> Any knowledge of a public domain 8051 disassembler which can rival IDA
in
>>> performance/code analysis?
>>>
>>> _     Elio.
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