The AT27C256R-90JU is a high-performance 256K EPROM (Erasable Programmable Read-Only Memory) chip from Atmel, now part of Microchip Technology. This memory component has a capacity of 256K bits, organized as 32Kx8, allowing for efficient storage and retrieval of data. Designed for applications requiring fast access times, it offers a maximum access time of 90 nanoseconds, making it well-suited for high-speed microprocessor systems. The AT27C256R-90JU operates within a wide voltage range, making it adaptable to various operating environments. Its JEDEC standard 32-lead PLCC (Plastic Leaded Chip Carrier) package ensures compatibility with standard PCB layouts, offering ease of integration into existing designs. This EPROM is erasable with ultraviolet light, allowing it to be reprogrammed multiple times, making it ideal for development, prototyping, and small-scale production runs. Its reliability, coupled with low power consumption and extended temperature range, makes it a viable option for a wide array of applications, including embedded systems, automotive, and industrial controls.