Memory Subsystem; Dram Memory; I/O Subsystem - NEC Versa 2500 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 2500 notebooks contain 16 MB of 70ns page-interleaved DRAM on the
system board. The notebook provides one extra memory slot for upgrading the DRAM
memory to 8 MB, 16 MB, 24 MB, 32 MB, 40 MB, & 48 MB using standard JEDEC or
EDO 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 2500 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:
T
Compatible with IBM AT architecture
T
Supports up to two 360K, 720K, 1.2M, or 1.44 MB floppy disk drives
T
Supports IBM PC/AT interface to IDE (Intelligent Drive Electronics)-type Win-
chester drives
T
Hardware or software configuration
T
Address decoding and strobe generator for game port
T
Supports two serial port functions
T
Supports one bi-directional IBM PS/2 compatible parallel port function
T
All functions can be enabled or disabled individually
T
Configuration Register can be easily selected
T
Only one 24 MHz crystal needed
T
100-pin plastic flat package