The NMC27C256QE150 is a 256Kbit (32K x 8) UV Erasable PROM (EPROM) manufactured by National Semiconductor, later acquired by Texas Instruments (TI). It provides non-volatile memory storage and is commonly used in applications where firmware or program code needs to be stored reliably.

Applications

• Embedded Systems: Used for storing firmware, boot code, and program code in embedded systems.
• Industrial Control Systems: Employed in industrial control systems for storing application software and configuration data.
• Instrumentation: Integrated into electronic test and measurement instruments for storing calibration data and instrument settings.
• Early Personal Computers and Arcade Games: Used for storing BIOS and game ROMs.

Features

• 256Kbit Capacity: Offers 256Kbits (32K x 8) of non-volatile memory storage.
• UV Erasable: Data can be erased by exposing the chip to ultraviolet (UV) light through a quartz window.
• Fast Access Time: Features a fast access time of 150ns (as indicated by '150' in the part number).
• JEDEC Standard Pinout: Adheres to the JEDEC standard pinout for easy replacement and compatibility.
• TTL Compatible: Compatible with TTL logic levels.

Benefits

• Non-Volatile Storage: Retains data even when power is removed.
• Reliable Data Storage: Provides reliable data storage for critical program code and data.
• Fast Access Time: Enables quick data retrieval for improved system performance.
• Wide Availability: Widely available and supported in various development tools and environments.

Additional Details

The NMC27C256QE150 requires a dedicated UV eraser for erasing the data. The erasure process typically takes several minutes. After erasure, the EPROM can be programmed using an EPROM programmer. The 'QE' in the part number likely refers to a specific package type or temperature range. These EPROMs were popular before EEPROMs and flash memory became widespread, offering a cost-effective solution for storing relatively stable program code. A quartz window on the package allows UV light to reach the memory cells for erasure. Care must be taken to protect the window from ambient light to prevent accidental erasure.