Thanks, DavidAlfa, for posting the initial link.
Those are the basic commands. It was later confirmed to work on all the models. Plus, an optional argument was discovered to dump ALL the NVRAM at once:
https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/msg1618642/#msg1618642Since the procedure is somewhat scattered through threads on eevblog and TekScopes, let me try to summarize the essentials here.
In short, the procedure to capture the calibration and other NV data is to send the GPIB commands:
key 0
earom? f
The format of the data returned is the starting location in NVRAM (which is 0 in this case), a colon, and then comma separated values from incrementing NVRAM locations.
On models later than the 2445/2465, you're going to get 255 16-bit words (510 bytes), which maps to 0x1E00 to 0x1FFD in the actual NV SRAM chip. The words are stored in big-endian format. The address range covers the calibration data and other opaque data currently unknown to us mere mortals.
To restore the data, you need to send it back to the scope one word at a time. The format of the argument is the location in NVRAM, a colon, and then the value:
key 0
earom 0:215;
earom 1:1908;
earom 2:1921;
earom 3:1921;
...
earom 253:16499;
earom 254:14;
earom 255:0;
Sending it back en-masse (i.e., replaying the one big line that the scope sent) does not work, at least not for me.
On the 2445/2465, you are only going to get 200 16-bit words, and not 255. Words 0-99 are from the EAROM on the main processor board, and 100-199 are from the EAROM on the buffer board.
Keep in mind that all numbers for the EAROM command are represented in DECIMAL and not hex, as it appears in the EXER 02 display.
As an example from the dump above, EAROM 1 is 1908 and is shown in EXER 02 as 0774. This is stored in the actual SRAM as 0x1E02: 0x07 and 0x1E03: 0x74.