• 80C51 Central Processing Unit
• 16k × 8 (89C536) or 64k × 8 (89C538), FLASH EPROM Program
Memory
• 512 × 8 RAM, externally expandable to 64k × 8 Data Memory
• Three 16-bit counter/timers
• Up to 3 external interrupt request inputs
• 6 interrupt sources with 2 priority levels
• Four 8-bit I/O por.