The design of a BiCMOS 50-MHz, 2.2-million transistor, second-level cache controller chip (CC) for a SPARC super-scalar CPU (PU) is described. This chip is designed to control up to 2 MB of second-level cache (E$) so that the effective memory latency is reduced, and to support two different multiprocessor (MP) system buses, the MBus and the Dynabus. CC isolates PU and E$, which operate with a faster processor clock, from the rest of the system, which may operate with a slower system clock, through multiple FIFOs (first in, first out's) and synchronizers. With the isolation, the PU can access E$ in a pipelined fashion with a peak rate of one double-word (64-bit/DW) every processor cycle for both read and write. >