INTRODUCTION
A member of the Intel family of 8-bit MCS 251 microcontrollers, the 8xC251TA/TB/TP/TQ is binary-code compatible with MCS 51 microcontrollers and pin compatible with 40-pin PDIP and 44-pin PLCC MCS 51 microcontrollers.

■ Real-time and Programmed Wait State Bus Operation
■ Binary-code Compatible with MCS® 51
■ Pin Compatible with 44-pin PLCC and 40-pin PDIP MCS 51 Sockets
■ Register-based MCS® 251 Architecture
    — 40-byte Register File
    — Registers Accessible as Bytes, Words, or Double Words
■ Enriched MCS 51 Instruction Set
    — 16-bit and 32-bit Arithmetic and Logic Instructions
    — Compare and Conditional Jump Instructions
    — Expanded Set of Move Instructions
■ Linear Addressing
■ 256-Kbyte Expanded External Code/Data Memory Space
■ ROM Options: 16 Kbytes (TB/TQ), 8 Kbytes (TA/TP), or without ROM
■ 16-bit Internal Code Fetch
■ 64-Kbyte Extended Stack Space
■ On-chip Data RAM Options: 1-Kbyte (TA/TB) or 512-Byte (TP/TQ)
■ 8-bit, 2-clock External Code Fetch in Page Mode
■ Fast MCS 251 Instruction Pipeline
■ User-selectable Configurations:
    — External Wait States (0-3 wait states)
    — Address Range & Memory Mapping
    — Page Mode
    — Extended Data Float Timings or 8xC251Sx Compatible AC Timings
■ 32 Programmable I/O Lines
■ Eight Maskable Interrupt Sources with Four Programmable Priority Levels
■ Three Flexible 16-bit Timer/counters
■ Hardware Watchdog Timer
■ Programmable Counter Array
    — High-speed Output
    — Compare/Capture Operation
    — Pulse Width Modulator
    — Watchdog Timer
■ Two Programmable Serial I/O Ports
    — Framing Error Detection
    — Automatic Address Recognition
■ High-performance CHMOS Technology
■ Static Standby to 24-MHz Operation
■ Complete System Development Support
    — Compatible with Existing Tools
    — MCS 251 Tools Available: Compiler, Assembler, Debugger, ICE
■ Package Options (PDIP and PLCC)