256 bytes RAM — the real constraint on firmware complexity
With 256 x 8 bits of RAM, every byte counts. The stack, global variables, and any buffering for SPI or UART transfers all share this pool. A typical firmware loop for reading the ADC, scaling the result, and sending it out over UART fits easily, but avoid dynamic allocation or large lookup tables. The 8 KB Flash is generous for the code space — the RAM is the tighter ceiling.
Industrial temperature rating and package reality
It's MSL 1 per TI's standard — no bake required before reflow if the sealed bag is intact. The 22 I/O lines are available on this 28-pin package, which is enough for a keypad, a small LCD segment driver, and a couple of sensor inputs.
TI continues to manufacture the MSP430x1xx series, and this part is available through franchised distribution.