Chapter 2
18
2.4
CACHE CONFIGURATION
The special feature of the mainboard is a built-in direct-mapped cache controller with optional write-
back or write-through operation that supports 128KB, 256KB, 512KB or 1024KB cache memory.
The mainboard has a built-in cache controller. It requires external SRAM as tag and cache memory.
The caching Scheme is direct mapping with selectable write-back or write-through operation. The
mainboard allows 128KB, 256KB, 512KB, and 1024KB cache configurations. Memory size is
selected by the hardware jumpers and the BIOS setup program.
2.4.1
UPGRADING CACHE
The mainboard is available with an optional 128KB, 256KB, 512KB or 1024KB cache memory on-
board. User can upgrade cache memory by installing additional SRAM (Static Random Access
Memory) chips in sockets U13-U20; U11.
The speed of the SRAM chips needed depends on the clock speed of the microprocessor:
25MHz clock requires 25ns (tag) and 25ns (data) SRAM chips.
33MHz, 40MHz clock CPU requires 20ns (tag) and 20ns (data) SRAM chips.