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1-6 Technical Information
High-performance features include:
n
pipelined 32-bit addressing
n
64-bit data
n
direct mapped write-back and write-through support
n
system support 256 kilobytes (KB) of asynchronous 15-ns secondary cache
The cache is connected directly to the processor address bus and uses physical addresses. A
bus feature known as burst enables fast cache fills. Memory areas (pages) can be designated
as cacheable or non-cacheable by software. The cache can also be enabled and disabled by
software.
The write strategy of the cache (primary and secondary) is write-back. If the write is a
cache hit, an external bus cycle is not generated and information is written to the cache. Any
area of memory can be cached in the system. Non-cacheable portions of memory are
defined by software. The cache can be cleared by software instructions.
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 the rest is
utilized as listed in Table 1-2. 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.
NEC's Flash ROM allows fast, economical BIOS upgrades. NEC Flash ROMs are
reprogrammable system and video EPROMs. With NEC's Flash ROM, a ROM BIOS
change:
n
is fast and easily done using a Flash utility
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eliminates the expensive replacement of ROM BIOS chips, and reduces system
maintenance costs
n
reduces inadvertent system board damage that can take place when replacing
ROMs
n
facilitates adopting new technology while maintaining corporate standards
n
gives network administrators company-wide control of BIOS revisions.
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.
Summary of Contents for POWERMATE P - SERVICE MANUAL 1995
Page 37: ...1 22 Technical Information ...
Page 169: ...Index 5 ...