GENERAL DESCRIPTION
The ISSI IS89C51 is a high-performance microcontroller fabricated using high-density CMOS technology. The CMOS IS89C51 is functionally compatible with the industry standard 80C51 microcontrollers.
The IS89C51 is designed with 4-Kbytes of Flash memory, 128 x 8 RAM; 32 programmable I/O lines; a serial I/O port for either multiprocessor communications, I/O expansion or full duplex UART; two 16-bit timer/counters; an six-source, two-priority-level, nested interrupt structure; and an on-chip oscillator and clock circuit. The IS89C51 can be expanded using standard TTL compatible memory.

FEATURES
• 80C51 based architecture
• 4-Kbytes of on-chip Reprogrammable Flash Memory
• 128 x 8 RAM
• Two 16-bit Timer/Counters
• Full duplex serial channel
• Boolean processor
• Four 8-bit I/O ports, 32 I/O lines
• Memory addressing capability
    – 64K ROM and 64K RAM
• Program memory lock
    – Lock bits (3)
• Power save modes:
    – Idle and power-down
• Six interrupt sources
• Most instructions execute in 0.3 µs
• CMOS and TTL compatible
• Maximum speed: 40 MHz @ Vcc = 5V
• Industrial temperature available
• Packages available:
    – 40-pin DIP
    – 44-pin PLCC
    – 44-pin PQFP