Detailed descriptions of the μPD7720 architecture are found in Chance (1990), Sweitzer (1984) and Simpson (1984). Briefly, the NEC μPD7720 runs at 4 MHz frequency with 128-word data RAM, 512-word data ROM, and 512-word program memory, which has VLIW-like instruction format, enabling all of ALU operation, address register increment/decrement operation, and move operation in one cycle.
