Instruments supported by V9.7 firmware:

   494A/P
   492A/P
   492B/P
   492PGM
   495/P
   497/P
   2753
   2754
   2755/A
   2756

Note: The 497/P and 494A/P analyzers are physically very similar instruments,
possibly identical.  However, the signal-counter feature is disabled in the 
497/P's firmware, at least in serial numbers after B020000.  It is possible 
to restore the counter functionality by resetting the 497/P's DIP switches to
'fool' the firmware into thinking it's installed in a 494A/P.  To do this --
or to install the 9.7 ROMS in a 494A/P -- set the DIP switches for "494A/P" 
in the table below:

         Memory board        Z-axis board
         ------------        -------------
495/P:   4 open              2,3,5,7 open; 1 closed for P-suffix version
494A/P:  3 open*             2,3,4,5,6,7 open; 1 closed for P-suffix version**
497/P:   2,3,4 open          3,4,6,7 open; 1 closed for P-suffix version
492B/P:  1,2 open
492A/P:  2 open

*: 2 open for 1 MHz filter, closed for 3 MHz
   1 open if 10/100 Hz filters not present
   1,2 open if 100 Hz filter present but not 10 Hz

**: 6 open for 100 kHz filter, closed for 300 kHz
    2,3,4,5,7 = unknown function (7 possibly Opt 07 for 75-ohm compatibility)

These switch settings were determined by empirical observation.  Some 
experimentation may be necessary depending on the options installed
in the instrument.

S1050 Settings.xls provided courtesy Justin Ogden of Ogden Labs.
49x & 275x firmware release history.xls provided courtesy Gerald Molenkamp