MEMORY ORGANIZATION
PROGRAM MEMORY: Up to 4 Kbytes of the program memory can reside on-chip (except 80C31BH). In addition the device can address up to 64K of program memory external to the chip.
DATA MEMORY: This microcontroller has a 128 x 8 on-chip RAM. In addition it can address up to 64 Kbytes of external data memory.
The Intel 87C51/80C51BH/80C31BH is a single-chip control-oriented microcontroller which is fabricated on Intels reliable CHMOS III-E technology. Being a member of the MCS® 51 controller family, the 87C51/80C51BH/80C31BH uses the same powerful instruction set, has the same architecture, and is pin-forpin compatible with the existing MCS 51 controller family of products.

■ High Performance CHMOS EPROM
■ 24 MHz Operation
■ Improved Quick-Pulse Programming Algorithm
■ 3-Level Program Memory Lock
■ Boolean Processor
■ 128-Byte Data RAM
■ 32 Programmable I/O Lines
■ Two 16-Bit Timer/Counters
■ Extended Temperature Range (-40°C to +85°C)
■ 5 Interrupt Sources
■ Programmable Serial Port
■ TTL- and CMOS-Compatible Logic Levels
■ 64K External Program Memory Space
■ 64K External Data Memory Space
■ ONCE Mode Facilitates System Testing
■ Power Control Modes
   • Idle
   • Power Down