Description
The AT89S4D12 is a low-voltage, highly integrated CMOS 8-bit microcomputer with 4K bytes of downloadable Flash program memory and 128K bytes of in-system reprogrammable Flash data memory. The device is manufactured using Atmel’s high density Flash memory technology and is compatible with the industry-standard MCS-51™ instruction set.

FEATUREs
• Compatible with MCS-51™ Products
• 128K Bytes of In-System Reprogrammable Flash data memory and 4K Bytes of Downloadable Flash Program Memory
   – Endurance: 1,000 Write/Erase Cycles per Sector
   – Data Retention: 10 Years
• Sector Programming: 128 Bytes/Sector
• Single 3.3V ± 10% Supply
• On-Chip 12 MHz oscillator
• Two-Level Program Memory Lock
• 256-Bytes Internal RAM
• 5 Programmable I/O Lines
• Serial Peripheral Interface (SPI) Channel
• Serial Program Downloading
• Dual Data Pointer Registers