[Techtoolslist] Fluke 9100 system EEPROM disambiguation

[Steve Larkins]

Nice work!

On Sat, 23 Apr 2022 at 23:33, Andrew Welburn <andy at andysarcade.net> wrote:

> hi all.
>
>   There's a 32-byte soldered-in I2C serial EEPROM (type X2444) that
> contains crucial hardware setup information use in the Fluke 9100 series
> systems. The values in this eeprom hold information pertaining to some
> calibrations as well as all basic I/O hardware. This information can all
> be set/changed with the use of floppy service disks in a working system.
>
>   If you happen to set the wrong floppy drive type in this menu, you can
> lock yourself out of being able to adjust anything, as well has having a
> non-working floppy drive.
>
>   You can re-program the chip in-circuit (in theory, but i didn't try
> it) or you can de-solder it, and dump the contents/reprogram it. The 32
> bytes might be a little cryptic, but with trial an error i have found
> out the following address map. It is not exhaustive, there are likely
> more things stored in here relating to IO mod or pod or probe
> calibrations accessed in the setup/calibration menus from a regular boot
> cycle, but for now, this is what i have discovered:
>
> offset          Purpose                 Notes
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> 00 to 03        Serial #                Little Endian
> 04              System/disk type        Note1
> 05 to 08        Probe offset            calibration values
> 0A              Disk err reporting      00=OFF 0A=ON
> 0C,0D           unknown                 do not change
> 0F              RAM size                Note2
> 11              Network Node            00 to F4 is valid
> 15              Floppy type             Note3
> 18 to 19        IEEE option             YES=04D7 NO=14D7
> 1A to 1C        site #                  Little Endian
> 1E to 1F        checksum                Note4
>
> Note1 = 42=9100/Miniscribe 76=9100/scsi512 66=9100+scsi256 00=9105/9050
>
> Note2 = 18=1.5mb 20=2mb 30=3mb 40=4mb 80=8mb F0=15mb
>
> Note3 = 00=Gotek 01=Canon 03=Sony 04=Mitsumi 05=Teac 06=CanonHD
>
> Note4 = BSD Checksum, but barrel-rotated right 10 bits then inverted
> see: http://www.andysarcade.net/personal/tech/fluke9100/andysum.zip
>
>   Big props to TheMogMinor/MooglyGuy for figuring out the checksum, as
> well as writing the utility and providing source code!
>
>   Now you can create a binary yourself, generate/apply a valid checksum
> and write this to the ROM and get yourself back in business.
>
> enjoy.
>
>
> --
> Andrew Welburn
> andys-arcade
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