256K X Flash Rom; Rom Bios; Vga Controller - NEC VERSA 6220 Service Manual

256K X Flash ROM

The N28F020 flash ROM is a 32-pin, plastic lead chip carrier (PLCC). The chip allows easy
updates to the system's BIOS if needed. More specifically, the ROM is flashed electroni-
cally, installing the latest BIOS revisions to the system. It is possible to reprogram the BIOS
up to 100,000 times. See Section 2, Setup and Operation, for BIOS update procedures.
The N28F020 provides the system upgrade capability as well as the following:
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256 KB memory
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Quick-Pulse Programming Algorithm
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150 nanoseconds (ns) maximum access time
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ETOX Nonvolatile flash technology
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CMOS low power consumption

ROM BIOS

The system uses a Flash ROM known as the system's ROM BIOS to store machine lan-
guage programs. The BIOS size is 256 KB, consisting of the system utility (for PC cards,
Auto Setup), system BIOS, video BIOS, and power management.
The BIOS programs execute the power-on self-test (POST), initialize CPU controllers, and
interact with the LCD indicator panel, diskette drive, hard drive, communication devices
and peripherals. The system BIOS also contains Auto Setup and provides VGA controller
support. The ROM BIOS is copied into RAM (shadowing) for optimum performance.
The ROM BIOS contains both the system and video BIOS. The system BIOS is located in
the upper portion of the device; video BIOS is located in the lower portion. System BIOS is
located between F0000h-FFFFFh.
The BIOS often changes after the product release to provide enhanced features or bug
fixes. To acquire the latest BIOS release, the ROM is flashed electronically, allowing the
BIOS update to occur without removing the ROM. See Section 2, Setup and Operation, for
BIOS upgrade procedures.

VGA Controller

The NeoMagic NMG4 is a PCI 64-bit Graphics Accelerator. The integrated programmable
linear address feature accelerates the graphics user interface (GUI) performance. The con-
troller also supports Hardware Multimedia and VESA interface standards. The controller
provides advanced power management that helps to minimize power usage in the following
modes:
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normal operation
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Standby (sleep) mode
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panel off power saving modes.
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