Cache tag RAMs offer 12-nsec validated match with extras. (Cypress Semiconductor's CY7B180 and CY7B181 memories)(Electro '92 Show Guide & Product Spotlight)(EDN-Product Update) (Product Announcement)

EDN, May, 1992 by Quinnell, Richard A.

The CY7B180 and CY7B181 cache tag RAMs not only offer 4k x 16-bit tag memory, they include functions such as chip-select decoding and the logic needed for validating matches. They also include two status bits for each memory location and an additional data port to speed copyback cache designs.

The devices' base structure is 4k x 18 bits. Each word location stores a 16-bit tag and two status bits. You use the devices for storing the lower-order address bits for the memory you have copied into cache. When the processor addresses a memory location, the tag RAMs respond with a match signal within 12 nsec if that address has been cached.

Several built-in functions can simplify your cache design. You can read from and write to the tag data and...

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