its because of that stupid "chip" you see on all of them. its actually a 1-wire EEPROM. it contains the ink levels, cartridge type, and fill date inside one eeprom.
I know this because I used to reprogram those on toner cartridges when i refilled them. I lost the program that did it though through a harddrive crash. sucked, i thought i had it in my emails but my emails did not, which coincidently was the same hard drive crash i lost the CAD file to my SCSI drive. Basically you would use any means to dump the EEPROM, which in my case was a 1-wire driver on an atmel and RS232 to read the bin off the eep.
the program would actually interpret the binary data dumped from the eeprom into actual legible information.
I know this because I used to reprogram those on toner cartridges when i refilled them. I lost the program that did it though through a harddrive crash. sucked, i thought i had it in my emails but my emails did not, which coincidently was the same hard drive crash i lost the CAD file to my SCSI drive. Basically you would use any means to dump the EEPROM, which in my case was a 1-wire driver on an atmel and RS232 to read the bin off the eep.
the program would actually interpret the binary data dumped from the eeprom into actual legible information.