• 80C51 Central Processing Unit – 4 Kbytes Flash (P89C51X2) – 8 Kbytes Flash (P89C52X2) – 16 Kbytes Flash (P89C54X2) – 32 Kbytes Flash (P89C58X2) – 128 byte RAM (P89C51X2) – 256 byte RAM (P89C52/54X2/.