Memory Subsystem; Dram Memory; Rom Memory; I/O Subsystem - NEC Versa 2400 Series Service Manual

3-6 Hardware Functional Overview

MEMORY SUBSYSTEM

The memory subsystem, implemented on the system board, includes ROM and DRAM
memory. Primary control for the memory subsystem is provided by the UMC 8890 System
Controller chipset.

DRAM Memory

The NEC Versa 240X notebooks contain 8MB (16MB for NEC Versa 243X) of 70ns
page-interleaved DRAM on the System board. The notebook provides one extra memory
slot for upgrading the DRAM memory to 8MB, 16MB, 24MB, 32MB, 40MB, & 48MB for
the NEC Versa 2400 Series) using standard JEDEC small-outline DIMM memory modules.
(Refer to Chapter 1 on System Upgrades to know more about how to upgrade the system
memory).

ROM Memory

The NEC Versa 2400 Series notebooks contains both the main system BIOS and the VGA
BIOS with Shadow BIOS capability.

I/O SUBSYSTEM

The I/O Subsystem of the notebook is implemented on the I/O Board using the NS
PC87336VLJ chipset. The supported I/O interface on the notebook includes the internal
hard disk drive interface, the internal floppy disk drive interface, the external printer port
interface, the external serial port, and the external PS/2 keyboard and mouse ports.
Feature's summary of the NC87336VLJ:
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Compatible with IBM AT architecture
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Supports up to two 360K, 720K, 1.2M, or 1.44MB floppy disk drives
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Supports IBM PC/AT interface to IDE (Intelligent Drive Electronics)-type Win-
chester drives
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Hardware or software configuration
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Address decoding and strobe generator for game port
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Supports two serial port functions
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Supports one bi-directional IBM PS/2 compatible parallel port function
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All functions can be enabled or disabled individually
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Configuration Register can be easily selected
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Only one 24MHz crystal needed
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100-pin plastic flat package