| Title: | Mathematics at DEC |
| Moderator: | RUSURE::EDP |
| Created: | Mon Feb 03 1986 |
| Last Modified: | Fri Jun 06 1997 |
| Last Successful Update: | Fri Jun 06 1997 |
| Number of topics: | 2083 |
| Total number of notes: | 14613 |
i am working on a program that automatically changes the CMOS settings of
PCs based on installed hardware.
For the newer lines of PCs they use CRC checksums :
Product A Product B
CRC signature : 93Ch CD9h
CRC mask : 3Fh FFFFh
in Product A : 29 bytes in CMOS are checked and the CRC result is 6 bits
in Product B : 54 bytes in CMOS are checked and the CRC result is 2 bytes.
I've looked at some books i have but all refered to 1 polynomial divisor and
none used the terminolgy 'CRC signature' and 'CRC mask'.
Can anyone shed some light please.
Maged
| T.R | Title | User | Personal Name | Date | Lines |
|---|---|---|---|---|---|
| 1925.1 | WAG | AUSSIE::GARSON | achtentachtig kacheltjes | Wed Dec 28 1994 16:23 | 10 |
re .0
I would imagine that some CRC algorithm is applied over the bytes in
CMOS giving the CRC signature. This is then masked (ANDed) with the CRC
mask and the result stored for future comparison when the CRC is re-
evaluated.
In order to update the CRC you would have to know which CRC algorithm
is being used i.e. if it's equivalent to the VAX CRC instruction, you
would have to know the polynomial being used.
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| 1925.2 | RUSURE::EDP | Always mount a scratch monkey. | Thu Dec 29 1994 08:41 | 10 | |
You're more likely to get the specific information you're looking for,
or a pointer to it, in the conference Noted::IBMPC-94, soon to become
Noted::IBMPC-95.
-- edp
Public key fingerprint: 8e ad 63 61 ba 0c 26 86 32 0a 7d 28 db e7 6f 75
To find PGP, read note 2688.4 in Humane::IBMPC_Shareware.
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