Advanced Micro Devices, Inc. Memory AM27S25A/B3A

The AM27S25A/B3A is a 4096-bit (512x8) bipolar registered Programmable Read-Only Memory (PROM) designed for microprogrammable controls and state machines. It features a fully decoded Schottky array and incorporates D-type master-slave data registers on-chip. The device supports three-state outputs that are compatible with low-power Schottky bus standards. This PROM includes an 8-bit parallel data register in the array-to-output path, allowing data storage while other data is being addressed, which is beneficial for pipelined microprogrammable control stores. The AM27S25A version offers enhanced performance with a 25 ns setup time and a 12 ns clock-to-output delay. It also provides both synchronous and asynchronous output enables, along with common asynchronous preset and clear controls. The device is packaged in a slim 24-pin, 300-mil lateral center package, occupying less board space compared to standard discrete PROM and register combinations. It consumes approximately half the power of separate PROM/register setups, contributing to improved system reliability. The use of platinum-silicide fuses ensures high reliability and fast programming with exceptional yields.