Need correct IOS to run SDM on a 2650XM

For a lab, I am trying to run SDM, on a 2650XM. but the report is it doesnt support the current IOS on the router, which is C2600-DZ-MZ-122-12C.BIN. sdm said to go the cisco.com/go/sdm and download another IOS. What IOS should I get? a basic base or one that supports encryption or what. As an aside, when I tried to download a maintenance release IOS for this router, it said I needed to have a "technical support services" agreement with Cisco. ..... But that's another story.

thanks

OK, how about this. I bought an updated flash with an updated IOS on it that should be supported by Cisco SDM. So I installed it and then at the prompt typed in the show flash command.

Is there a Cisco hardware expert who can tell me what a 2 partition flash is?

System flash directory, partition 1:
File Length Name/status
1 10770496 c2600-ds-mz.122-12c.bin
2 11768 crashinfo_20050922-135739 [deleted] [invalid checksum]
[16777216 bytes used, 0 available, 16777216 total]
16384K bytes of processor board System flash (Read/Write)


System flash directory, partition 2:
File Length Name/status
1 18213500 c2600-advsecurityk9-mz.124-9.T2.bin
[18213564 bytes used, 14816580 available, 33030144 total]
32768K bytes of processor board System flash (Read/Write)

lthe flash /2 is the new flash chip. what the flash partition 1 I don't know

thanks

the flash /2 is the new flash chip. what the flash partition 1 I don't know

Isn't it your original flash, since it seams to contain the same image file you mentioned before. Or did you remove your old flash?