The UPD421000C-80 is a 1 Mbit Dynamic Random Access Memory (DRAM) chip manufactured by NEC. It is designed for use in a variety of memory applications where cost-effectiveness and reasonable speed are important.

Applications

• Main memory in older personal computers
• Memory modules in workstations and servers
• Video memory in graphics cards
• Memory for embedded systems
• Laser printers and other peripherals

Features

• 1 Mbit storage capacity
• Access time of 80ns, indicating the speed at which data can be read or written
• Dynamic RAM technology: Requires periodic refresh cycles to retain data
• Multiplexed address inputs, reducing the number of pins required
• Single 5V power supply operation

Benefits

• Cost-effective memory solution for applications not requiring the highest speeds
• Relatively large memory capacity for its time of manufacture
• Industry-standard pinout and interface, making it compatible with many existing systems
• Wide operating voltage range provides design flexibility
• Reduced system size due to multiplexed addressing

Additional Details

The UPD421000C-80 is commonly organized as 128K x 8 bits. The DRAM requires refresh cycles, typically every few milliseconds, to prevent data loss. The refresh operation involves reading and rewriting each row of memory cells. The part is packaged in a standard DIP package. For detailed specifications, including power consumption, timing diagrams, and operating conditions, refer to the NEC datasheet for the UPD421000C-80. Proper decoupling capacitors are essential for reliable operation. Careful attention should be paid to timing requirements during read, write, and refresh cycles to avoid data corruption.