48-VQFN package and board-fit
The MSP430F4260IRGZR ships in a 48-VFQFN exposed-pad package (7x7 mm body, supplier device package 48-VQFN). At 0.5 mm pitch, the outer rows fan out between the pad vias; a two-layer board breaks out all 32 I/O if the trace width stays under 0.15 mm.
Flash and RAM — the tight constraint is the 256 bytes
24 KB of flash (24K x 8 plus 256 bytes of information memory) holds the application code and constant tables. The 256 x 8 RAM is the real limiter — no dynamic allocation, no large stack frames. A firmware image that calls a 200-byte ISR with nested functions will overflow the stack on the first interrupt. The internal oscillator at 8 MHz means the CPU16 core executes one instruction per clock cycle on most operations; the 8 MHz ceiling is the throughput limit, not the flash access time.
Mixed-signal peripherals — LCD, ADC, DAC on one die
This MSP430x4xx part integrates an LCD driver, a 16-bit sigma-delta ADC (one channel), and a 12-bit DAC. The brown-out reset and power-on reset circuits are on-chip — no external supervisor needed for battery-powered wake-up. The 32 I/O lines include segment and common outputs for the LCD; the ADC and DAC share pins with the port, so the firmware must reconfigure the pin mux between analog and digital functions at run time.
TI lists this part as Active; no discontinuation notice or last-time-buy window has been issued.