Four MCM44256B modules comprise a full 4 MB of secondary cache for the R4000 processor. Each module contains nine MCM6729DWJ fast static RAMs for a cache data size of 256K x 36. The tag portion, dependent on word line size, contains either two MCM6729DWJ or one MCM6726DWJ fast static RAMs. All input signals, except A0 and WE are buffered using 74FBT2827 drivers with series 25 Ω resistors.
The MCM6729DWJ and MCM6726DWJ are fabricated using high–performance silicon–gate BiCMOS technology. Static design eliminates the need for internal clocks or timing strobes.
All 4MB R4000 supported secondary cache options are available.

• Single 5 V ± 10% Power Supply
• All Inputs and Outputs are TTL Compatible
• Fast Module Access Time: 12/15/17 ns
• Zero Wait–State Operation
• Unified or Split Secondary Cache is Supported
• Word Line Sizes of 4, 8, 16, and 32 are Available (See Ordering Information for Details)
• Decoupling Capacitors are Used for Each Fast Static RAM and Buffer, Along with Bulk Capacitance for Maximum Noise Immunity
• High Quality Multi–Layer FR4 PWB with Separate Power and Ground Planes