Memory sizing and core throughput
The MSP430F6636IPZ carries 128 KB of program flash and 18 KB of RAM on a 16-bit MSP430 CPUXV2 core clocked at 20 MHz. For a typical USB CDC class application with a 4 KB buffer pool and a 32 KB firmware image, roughly 14 KB of RAM remains for the application heap and stack — enough for moderate data logging or sensor fusion without external memory.
Peripheral set for mixed-signal control
The 74 GPIOs in the 100-LQFP package leave room for a parallel LCD data bus, keypad matrix, and external sensor interrupts without a port expander.