[W126 Coupe] What is a checksum ?

[Richard Hogarth]

Checksum-
A calculated value that is used to test data integrity. Errors can occur
when data is transmitted or when it is written to disk. One means of
detecting such errors is the use of a checksum. A value is calculated for a
given chunk of data by sequentially combining all the bytes of data with a
series of arithmetic or logical operations. After the data is transmitted or
stored, a new checksum is calculated and compared with the original one. ...
 
<http://www.intermec.com/eprise/main/Intermec/Content/About/GlossarySubpages
/Glossary_CD>
www.intermec.com/eprise/main/Intermec/Content/About/GlossarySubpages/Glossar
y_CD
 
-RPH
 
Those last 3 digits may refer to all sorts of things like batch numbers,
manufacturing plant, chip version,  etc. 
What is important is the code that is burned into the EPROM is th right one.
You can check the internet for guys with EPROM burners. They can read the
code from an old one or the proper code can be researched and usually
downloaded. 
 
 


  _____  


That is quite likely, but I've never burnt an EPROM.  Further, the EPROM
that's in it is not the right one - it is 2287355758 and should be a
2287355316.  That number may refer to the program, I don't know.  There does
seem to be, or seems to have been, a bit of horse trading in EPROM chips.
All the talk of chips/programs for 560SEC revolves around the chip used in
the 220kW version (300hp).
 
The details I have (and I don't know exactly what they all mean) is:
CIS unit = 0280800156 or 0280800157
Eprom = 2287355316
Checksum = 5CF5
Don't know what this last one is but have seen it about as a specification
or hint or something, given along with checksum etc: MER560.ORI
The sites that discuss EPROM tweaking are all foreign language sites and
somewhat old, or at least it seems to be from what I can tell.
 
Robert

Robert,
 
 I know it could be a long shot, but is it not possible that if you burn a
new Eprom with the correct program (the one you know works in the original
unit), that it could solve the problem. The unit you have as the replacement
might have just that one difference. That might just be the program itself
that the Eprom contains.
 
Just a thought,
Vance.
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