DESCRIPTION
The Philips 8XC51/31 is a high-performance static 80C51 design fabricated with Philips high-density CMOS technology with operation from 2.7V to 5.5V.
The 8XC51/31 contains a 4k × 8 ROM, a 128 × 8 RAM, 32 I/O lines, three 16-bit counter/timers, a six-source, four-priority level nested interrupt structure, a serial I/O port for either multi-processor communications, I/O expansion or full duplex UART, and on-chip oscillator and clock circuits.

FEATURES
• 8051 Central Processing Unit
   – 4k × 8 ROM (80C51)
   – 128 × 8 RAM
   – Three 16-bit counter/timers
   – Boolean processor
   – Full static operation
   – Low voltage (2.7V to 5.5V@ 16MHz) operation
• Memory addressing capability
   – 64k ROM and 64k RAM
• Power control modes:
   – Clock can be stopped and resumed
   – Idle mode
   – Power-down mode
• CMOS and TTL compatible
• TWO speed ranges at VCC = 5V
   – 0 to 16MHz
   – 0 to 33MHz
• Three package styles
• Extended temperature ranges
• Dual Data Pointers
• Security bits:
   – ROM (2 bits)
   – OTP/EPROM (3 bits)
• Encryption array—64 bytes
• 4 level priority interrupt
• 6 interrupt sources
• Four 8-bit I/O ports
• Full–duplex enhanced UART
   – Framing error detection
   – Automatic address recognition
• Programmable clock out
• Asynchronous port reset
• Low EMI (inhibit ALE)
• Wake-up from Power Down by an external interrupt (8XC51)