• 80C51 Central Processing Unit – 4 kbytes ROM/EPROM (80/87C51X2) – 8 kbytes ROM/EPROM (80/87C52X2) – 16 kbytes ROM/EPROM (80/87C54X2) – 32 kbytes ROM/EPROM (80/87C58X2) – 128 byte RAM (80/87C51X2 an.