Secondary Cache; System And Video Bios - NEC POWERMATE V Service Manual

1-8 Technical Information
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PowerMate V100 — 100-MHz processor with internal speed of 100 MHz and
external speed of 66 MHz.
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PowerMate V133 — 133-MHz processor with internal speed of 133 MHz and
external speed of 66 MHz.
Each processor has 16 KB of write-back primary cache and a math coprocessor. The 16 KB
primary cache provides 8 KB for instructions and 8 KB for data.
The processor is an advanced pipelined 32-bit addressing, 64-bit data processor designed to
optimize multitasking operating systems. The 64-bit registers and data paths support 64-bit
addresses and data types.
To use the Pentium processor's power, the system features an optimized 64-bit memory
interface and complementary asynchronous pipelined 256-KB secondary cache.
The processor is compatible with 8-, 16-, and 32-bit software written for the Intel386™,
Intel486™, and Pentium processors.
To accommodate future technologies and work requirements, the Pentium processor comes
in a 320-pin zero insertion force (ZIF) socket. The socket provides an upgrade path to the
next generation processor.

Secondary Cache

The system board contains 256 KB of secondary cache, external to the processor. The first
release shipped uses 15-ns asynchronous SRAM (PowerMate V90 and V100) or 20-ns
asynchronous SRAM (PowerMate V75) cache. The second release of the PowerMate V
series ships with 15-ns synchronous pipe line burst cache.
Cache allows data to be sent or received from cache with one wait state burst. Cache
memory improves read performance by holding copies of code and data that are frequently
requested from the system memory by the processor. Cache memory is not considered part
of the expansion memory.

System and Video BIOS

The system and video BIOS are stored in a 1 MB (128 KB by 8) flash memory device
(Flash ROM). The system BIOS uses 64 KB, the video BIOS uses 32 KB, and 32 KB is
reserved. The system BIOS is capable of being shadowed and cached through the system's
Setup utility (see Section 2 for Setup information). System BIOS is write protected and
automatically enabled.
The BIOS programs execute the Power-On Self-Test, initialize processor controllers, and
interact with the display, diskette drives, hard disks, communication devices, and
peripherals. The system BIOS also contains the Setup utility. The hardware setup default
copies the ROM BIOS into RAM (shadowing) for maximum performance.