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Author Topic: old motronic (8051 based) disassembly  (Read 12770 times)
alex-84
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« on: August 16, 2019, 07:23:46 AM »

Hello,
sorry if I make mistakes in english I'm french

I would like to disassemble the code of a bosch MP3.2 calculator
this calculator is used on peugeot turbo petrol engines before 2000

it's the first time I do this job

I think I managed to properly disassemble my file, but I would still like someone to confirm if I'm on the right track

and know once I'm at this point if there are any specific advice as to which function is what

thanks.

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alex-84
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« Reply #1 on: August 17, 2019, 03:04:18 AM »

I have a question about axes signaturebytes and ram addresses?

for example I know that on this ecu the rpm axis is signed 3B, the manifold pressure is 43, water temperature is 3A ...

and sometimes in assembly code there are ram addresses that carry the same values:

Code:
		mov	MD1, B		; Multiplication/Division Register 1
mov MD4, RAM_43 ; Multiplication/Division Register 4
mov MD5, #0 ; Multiplication/Division Register 5

Code:
		mov	B, A		; B-Register
mov A, RAM_3B
cjne A, B, code_4FAA ; B-Register

Is there a relationship?
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prj
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« Reply #2 on: August 17, 2019, 12:49:10 PM »

http://m232.org

Download my commented M2.3.2 disassembly from github, it will answer a lot of your questions Wink
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alex-84
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« Reply #3 on: August 17, 2019, 01:00:10 PM »

Hello PRJ,

I saw part of your work this afternoon on the S2 forum, I was registering to contact you!

thank you for your help, I'm going to read  Wink
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alex-84
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« Reply #4 on: August 18, 2019, 04:12:12 AM »

is the .idb file to open?

because i have ida pro v6.1 which tells me "file too recent"

and ida freeware v7.0.1 which does not seem to want to open it ...

thanks.
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prj
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« Reply #5 on: August 18, 2019, 05:48:42 AM »

Well then you need newer IDA Pro, V7 or V7.1 at the very least.
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alex-84
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« Reply #6 on: August 18, 2019, 06:55:38 AM »

if it is not too complicated could you post a text version or other extention of this file?

I have a hard time finding on the net a more recent version of ida,

it does not pose any problem to me to pay licenses for software like winols that I use every day,

but not for a software of which I do not know how to use still and i which maybe not re-use...

thanks.
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biela
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« Reply #7 on: September 06, 2019, 06:44:14 AM »

Hello,
sorry if I make mistakes in english I'm french

I would like to disassemble the code of a bosch MP3.2 calculator
this calculator is used on peugeot turbo petrol engines before 2000

it's the first time I do this job

I think I managed to properly disassemble my file, but I would still like someone to confirm if I'm on the right track

and know once I'm at this point if there are any specific advice as to which function is what

thanks.



Hello

In 0261200809.asm file, code_6234 seems to be main loop.

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Jonathan226
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« Reply #8 on: April 04, 2021, 12:20:19 PM »

Hello Alex,

please, did you figure it out ? I'm also trying to disassemble MP3.2 ecu, but no luck. Do you have any new info ?
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alex-84
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« Reply #9 on: April 04, 2021, 12:27:01 PM »

I didn’t keep trying to disassemble, but when I have a little more time ahead of me I will get back to it
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Jonathan226
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« Reply #10 on: April 04, 2021, 03:47:43 PM »

I was just curious if you've found anything new. I'm currently trying to figure out maps, but it is slow and difficult task for me, when I see those things for first time. Yet I'm trying my best, I would love to keep MP3.2 on TCT engine without moving on speeduino.
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prj
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« Reply #11 on: April 05, 2021, 01:50:00 PM »

You can find maps with your eyes closed in those old Motronics.
Or at least I can.
Without any disassembly whatsoever.

And if you want to know how something works the functions are so simple, you can just work it out from the asm.

Nr1 is to define the "common" functions. Like multiplication, subtraction, addition, shifting, map lookup and so on and so forth, after that the code becomes very simple to read.
As I said already before, download my IDA database, it is pretty generously labeled. If you have any RE experience this should not take you long.

Truth be told, when I started with this back in 2010, then it did take me a few years to figure out most of the parts of the ECU and start writing my own code, logger etc.
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Jonathan226
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« Reply #12 on: April 11, 2021, 01:53:40 PM »

Alright, I'll look into it ! Thank you
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rmrmd1956
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« Reply #13 on: April 25, 2021, 03:23:18 PM »

http://m232.org

Download my commented M2.3.2 disassembly from github, it will answer a lot of your questions Wink

I hate to be so stupid but can you give me a link to the .i64 disassembly?
Or do you just have the 32 bit disassemble.
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prj
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« Reply #14 on: April 26, 2021, 03:43:29 AM »

I hate to be so stupid but can you give me a link to the .i64 disassembly?
Or do you just have the 32 bit disassemble.

Why would you need 64 bit IDA to disassemble a 8 bit uC?
64 bit IDA is only needed if you want to disassemble x64 or other 64 bit processors. There is no reason to use it otherwise.
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