This slide shows a part number breakdown using 23K256T-I/SN as an example. A “23” prefix designates a serial SRAM device. The second character determines the voltage range. “K” parts can operate from 2.7 to 3.6V, so are compatible with most microcontrollers. “A” parts operate from 1.5 to 1.95V in order to work with low-power ASIC devices. The third code determines the memory size: 640 for 64kb and 256 for 256kb. If there is a T in the next slot, it is shipped in tape and reel. Blank means it will be packed in tubes. Finally the last 2 places determine the temperature range, “I” being industrial temp and “E” being extended temp. The remaining digits call out the package/case. The devices are available in 8-lead SOIC, TSSOP, and DIP packages.