The program memory is 1 KB (1K x 8) plus a separate 256-byte information memory segment. That is a tight firmware footprint — suitable for a single control loop, state machine, or simple protocol bridge. The 128 x 8 RAM is likewise modest; expect to manage variables carefully. This part is not for data-logging or multi-protocol stacks, but for a dedicated sensor interface or actuator driver the Flash is adequate. The information memory can hold calibration constants or bootloader flags without wearing the main array.
The MSP430F2101TPWR carries an end-of-life (hot) lifecycle status. That means TI has issued or is in the process of issuing a last-time-buy notice. New-production builds through authorized channels are winding down. If you are qualifying a replacement, look at pin-compatible siblings in the MSP430F2xx family with larger Flash, but verify the exact footprint and peripheral set against the 20-TSSOP layout.