Intro to NEC PC-9800 World

Table of Contents

  1. Overall
  2. History
  3. Features
  4. Comparison with IBM PC/AT
  5. Culture
  6. References

1. Overall

This document describes NEC PC-9800 series PCs (the original, predominant PC in Japan) about its history, features and differences from IBM PC/AT. The author emphasizes historical and cultural view as well as technical view, as the former may be harder than the latter for people outside Japan to know.

Supposed readers are programmers who have to write applications for PC-98, otaku people who love Japanese anime or H-games, or other people who are interested in PC-98 world.

By the nature of this document, the word "PC" is used to refer to not only IBM PC and compatibles but also personal computers in general.

Notice: the author is familiar with traditional PC-98 (until PC-9801DA/FA) but not with recent PC-98 (98MATE/FELLOW and later). Descriptions about recent models may be insufficient or contain some unintentional mistakes.

PC-98 is:

PC-98 is NOT:

2. History

2.1 Brief History of PCs in Japan

2.2 History of PC-9800 series

NEC provides family trees of PC-9800 series.

2.2.1 Archaic desktop PC-98

2.2.2 Traditional desktop PC-98

2.2.3 Modern desktop PC-98

2.2.4 Laptop/notebook PC-98

2.2.5 High-end and specialized PC-98

2.3 The End of PC-98

In November 1997, NEC announced the end of PC-9800 series. Precisely, they proudly announced a new PC series named "PC98-NX", that are designed based on Microsoft's PC98 specification. Yes, they are basically a PC/AT compatible. Don't be confused between PC-98 and PC98.

PC98-NX series has a wide variety from a palmtop model to a desktop model and a small server model. They are somewhat "radically" designed PC98 as follows:

NEC says "they are new generation PCs, neither PC-9800 nor PC/AT compatibles". In fact, people may feel hesitation to call PC98-NX "PC/AT compatibles" because they are based on PC98 specifications, that is, they are partly denying traditional PC/AT architecture such as ISA expansion slots. However, the author suspects that this rhetoric of NEC shows that they wanted to avoid to be blamed "NEC has abondoned PC-9800 and switched to PC/AT compatibles." At least, PC98-NX is never PC-9800; software for PC-9800 never works on PC98-NX. The name "PC98-NX" looks like a camouflage to conceal from users difference between PC-9800 and PC98. In addition, "NX" is drawn more or less bigger than "PC98" in PC98-NX's logo. IMO this fact implies that NEC tries to emphasize "NX" rather than "PC98", for "PC98" will get obsoleted as time passes. "PC98" is a mere bridge with which NEC switches from PC-9800 to PC/AT compatibles.

NEC also announces they will continue to support PC-9800, but it is obvious to everyone that NEC is switching from PC-9800 to PC98-NX and PC-9800 will disappear soon. PC-9800 is finally declared to end in its 15th anniversary.

3. Features

3.1 CPU

3.2 Peripherals

4. Comparison with IBM PC/AT compatibles

4.1 Similarity

Overall architecture and environments are similar between PC-98 and PC/AT.

Item PC/AT PC-98
Ancestors RT/PC PC-8000/8800
CPU Intel x86 and compatibles
Conventional memory 640KB
Extended memory usage EMS, XMS, VCPI, DPMI
Traditional 16-bit bus ISA bus C-bus
High-end model & 32-bit bus PS/2, Micro Channel, (EISA) PC-H98, NESA bus
Temporary 32-bit local bus VL-bus A-MATE local bus
Current 32-bit local bus PCI
expansion bus for notebooks PC Card (PCMCIA)
Operating systems BASIC, MS-DOS, Windows, Windows NT, OS/2, UNIX, NetWare, ...
Server model PS/2 Server, PC Server SV-H98
Notebooks ThinkPad 98NOTE

4.2 Differences

Nowadays, PC-98 is getting more and more similar to PC/AT compatibles due to hardware cost merit and ease of porting system software. The characteristics of PC-98 listed below may be sometimes of traditional models rather than recent ones in order to emphasize differences from PC/AT.

Differences: Hardware

Item PC/AT PC-98
Original CPU & bus width 8088, 8 bits 8086, 16 bits
I/O address decoded 10 bits 8 bits
system resources 16 IRQs, 8 DMA channels 16 IRQs, 4 DMA channels
Video circuit Video card Built-in & video card
Text char set ASCII & European chars ASCII & Japanese chars
Graphic resolution over 640x480x16(HF 31kHz) over 640x400x16(HF 24kHz)
Text and graphics exclusive superimposed
floppy drives typically 1, max 2 typically 1 or 2, max 4 (or more)
5 1/4" floppy 360KB, 1200KB 640KB, 720KB, (1200KB), 1232KB
3 1/2" floppy 720KB, 1440KB 640KB, 720KB, (1200KB), 1232KB, 1440KB
hard drive I/F IDE, SCSI SASI->SCSI, IDE
Keyboard layout US, European, Japanese, ... Japanese
Serial ports 8250/16550, max 115.2kbps 8251/16550, max 38.4k/115.2kbps
Parallel (printer) port bidirectional uni/bidirectional
Sound beep, Sound Blaster etc. beep, FM sound, PCM etc.

Differences: Peripheral connectors

Item PC/AT PC-98
CRT display D-sub shrink 15-pin (3 rows) D-sub 15-pin (2 rows)
Keyboard AT(DIN 5-pin), PS/2(mini-DIN 6-pin) mini-DIN 6-pin
Serial ports D-sub 9/25-pin male D-sub 25-pin female
Parallel (printer) port D-sub 25-pin female Amphenol 14-pin male
mouse serial, PS/2 bus (D-sub 9-pin)
SCSI SCSI-1 standard (Amphenol 50-pin full-pitch)/
SCSI-2 standard (D-sub 50-pin half-pitch)
Amphenol 50-pin half-pitch

Differences: Disk Partitioning and Booting

Item PC/AT PC-98
Bootable device 1st floppy drive, 1st hard drive, (CD-ROM) Any floppy drive, any hard drive, MO drive etc.
disk partitions primary(max 4)/extended(max 1) max 16
multiple OS boot difficult standardized, easy
Drive letter assignment A:,B:=floppy drives,
C:=hard drives
A:=boot device (floppy or hard drive), Q:=CD-ROM (customary)

98's partitioning and booting is much easier and more flexible than PC/AT.

Reflecting this flexibility, drive letter assignment rule is much different from PC/AT. In general, the boot device will be assigned to A:, other devices following.

Therefore, YOU MUST NOT ASSUME C: IS HARD DRIVE! Most oversea software for PC/AT is written under this assumption and sometimes hard to install on 98.

Differences: Miscellaneous

Item PC/AT PC-98
Born on 1981 (IBM The PC) 1982
Inherited legacy None Much legacy from PC-8000/8800
hardware/software specification basically open basically closed
Compatible machine manufacturers Quite many Few (EPSON etc.)
Initiative IBM -> Compatible manufactures -> MS NEC
Market Worldwide Japan (& few oversea otaku people:-)

5. Culture

5.1 Hardware

5.2 Software


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