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.
NEC provides family trees of PC-9800 series.
The original PC-9801.
8086/5MHz 128KB RAM 640x400, digital 8 colors C-bus slot x 6 external floppy drives (option) 298,000yen
Peripheral devices for PC-8000/8800 series can be connected. However, 98 was still a high-end machine at that time.
98 begins to spread in this age.
8086/8MHz
PC-9801E: no internal floppy drives (for owners of external drives) PC-9801F: internal 5" 2DD(640KB/720KB) floppy drive(s) PC-9801M: internal 5" 2HD(1MB/1.2MB) floppy drive(s)
Bus mouse is adopted as pointing device.
PC-9801VM is an epoch-making model that established standard specifications of classical 98. 98 gained a predominant market share in this age.
V30/10MHz (V30 is 8086/80186-compatible, faster CPU by NEC) 640x400, 16 colors of analog 4096 colors, internal 5" 2HD/2DD dual-mode floppy drives
PC-9801VX is a 286 version of VM.
98 began to adopt 3.5" floppy drives.
PC-9801U: V30, 3.5" 2DD x2 PC-9801UV: V30, 3.5" 2HD/2DD x2 PC-9801UX: 286, 3.5" 2HD/2DD x2
The mainstream 98 acquired 386 CPU.
PC-9801RA 386DX/16-20MHz, 5" 2HD/2DD x2 PC-9801RS 386SX/16-20MHz, 5" 2HD/2DD x2 PC-9801RX 286 /16-20MHz, 5" 2HD/2DD x2 PC-9801ES 386SX/16-20MHz, 3.5" 2HD/2DD x2 PC-9801EX 286 /16-20MHz, 3.5" 2HD/2DD x2
5" and 3.5" models are integrated. /U shows 3.5" floppy model.
PC-9801DA,DA/U 386DX/20MHz PC-9801DS,DS/U 386SX/16MHz PC-9801DX,DX/U 286
F stands for "File slot", proprietary expansion bay for storage devices.
PC-9801FA,FA/U 486SX/16MHz PC-9801FS,FS/U 386DX/16MHz PC-9801FX,FX/U 386SX/16MHz
At this time, 98 is threatened by attack of PC/AT compatibles with DOS/V. 98 faced and had to compete PC/AT's cost/performance.
98's counterattack against PC/AT compatibles. 98MATE is designed for use with Windows 3.x and 98FELLOW is for use with MS-DOS.
98 continues to adopt PC/AT component technologies.
Now 98 desktop has three brands.
ValueStar: advanced desktop X-MATE: business desktop CanBe: personal/family desktop
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.
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 |
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.
| 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. |
Traditionally, PC-98 has been using a 640x200(15kHz) or 640x400(24kHz) display monitor. However, modern PC-98 supports an (S)VGA display.
Traditional C-bus expansion boards are wide and almost square shape while ISA/PCI cards are rectangle shape. C-bus expansion slots are covered with removable slot covers. You can install or remove C-bus boards without opening the case of your PC-98.
N.B. C-bus expansion adapters are usually called "boards", while ISA adapters are usually called "cards". This difference is interesting as it implies difference of size and shape between them.
Recent PC-98 has PCI slots.
Unlike PC/AT, which basically supports only 2 floppy drives, PC-98 can support max 4 drives per medium type. Below are supported medium types. Underlined are widely used formats.
| medium type | capacity | PC/AT |
| 8" 2D | 1MB | N/A |
| 5 1/4" 2D | 320/360KB | 5 1/4" 360KB |
| 5 1/4" 2DD | 640/720KB | N/A |
| 5 1/4" 2HD | 1200/1232KB | 5 1/4" 1200KB |
| 3 1/2" 2DD | 640/720KB | 3 1/2" 720KB |
| 3 1/2" 2HD | 1200/1232/1440KB | 3 1/2" 1440KB |
One remarkable characteristic of PC-98 floppy drives is that 5 1/4" drives and 3 1/2" drives are logically equivalent (except 3 1/2" 1440KB). You don't have to distinguish them, for example, when you run DISKCOPY.
External SASI hard drives (max 40MBx2) were used in early days.
NEC released a standard SCSI adapter board named PC-9801-55. However, for a certain reason, this adapter did not recognize hard drives made by manufacturers other than NEC. So peripheral device manufacturers bundled their own "55-compatible" SCSI adapter board with their SCSI hard drives. Thus many 55-compatible SCSI boards were supplied and became the de facto standard. (However, serious incompatibility problems took place because CHS translation parameters were different from manufacturer to manufacturer.)
Anyway, external SCSI hard drives gradually replaced SASI drives and became the standard storage device for PC-98.
As SCSI hard drives spread wide, other SCSI devices (such as CD-ROM drives and MO disk drives) also became common. In particular, MO disk drives are well supported by SCSI adapters and NEC MS-DOS. You can use an MO disk drive without installing any additional device drivers, and you can even boot an operating system from an MO disk. This is one of the reasons why 3 1/2" MO disks are now the most widely used removable medium in Japan.
NEC adopted internal IDE hard drives since 98MATE/FELLOW due to lower cost. Later they adopted ATAPI CD-ROM drives too. IDE hard drives and CD-ROM drives are now predominant also in PC-98, like PC/AT compatibles.
Ancient PC-98 has only beep sound. NEC shipped an FM-synthesizer sound board named PC-9801-26. Although it did not have a very rich sound generator (3 FM channels and 3 SSG channels), this board and its compatibles became standard sound boards as much game software supported them.
98MATE was shipped with a new, enhanced FM sound generator (6 FM channels, 5 rhythm channels and 3 SSG channels) with CD-quality PCM sound. This sound generator was also released as a C-bus sound board named PC-9801-86, so this feature is called "86 sound generator". Again many DOS-based game titles supported this sound generator as well as 98MATE's 256-color graphic screen. This sound generator is a must for DOS-based game players even now.
Recent PC-98 models (X-MATE and later) have PCM sound generator dedicated for use under Windows.
| 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 |
| 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.
| A: | 1st floppy drive |
| B: | 2nd floppy drive |
| C: | active primary partition of 1st hard drive |
| D:, E:, ... | other partitions, additional drives |
Suppose you have 2 floppy drives and 2 partitions in a hard drive.
If you boot from floppy (from either 1st or 2nd drive)
| A: | 1st floppy drive |
| B: | 2nd floppy drive |
| C: | 1st partition |
| D: | 2nd partition |
| E:, F:, ... | other partitions, additional drives |
If you boot from hard drive (from either 1st or 2nd partition)
| A: | 1st partition |
| B: | 2nd partition |
| C: | 1st floppy drive |
| D: | 2nd floppy drive |
| E:, F:, ... | other partitions, additional drives |
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.
| 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:-) |
All materials are in Japanese unless otherwise specified.
Level: intermediate - professional Audience: programmers
This 4-volume encyclopedia describes PC-98 hardware, BIOS calls and related technical information. Considered as the official source of PC-98 technical information. CD-ROM edition is also released.
Level: intermediate - professional Audience: programmers
This book is the authorized source of programming information about PC-9801-55, NEC's de facto standard SCSI board, and compatibles. It describes specification of each SCSI BIOS call. Unfortunately it is now hard to obtain.
Level: professional Audience: programmers
The title says it all. A valuable collection of undocumented BIOS call, I/O ports and BIOS work area.
Level: professional Audience: programmers
This book explains superb programming techniques with complete source codes to make full use of PC-98 hardware ability. Indispensable for advanced PC-98 programmers.
Level: intermediate Audience: programmers
Average technical book for PC-98 programmers. Includes information on PC-9821 256-color graphics.
Level: intermediate Audience: programmers
Looks like a plain OS textbook from the title, but contains a number of useful, sometimes undocumented, information and techniques. Includes information about PC-98 BIOS calls.
Level: entry Audience: general users
This book is meant for general users rather than programmers, like "Macintosh Bible". Useful to know the world and culture around PC-98.
Level: entry - intermediate Audience: all users
This book criticizes most models of PC-98 and EPSON's compatibles. Precious material to learn PC-98 history as well as characteristics of each model.
Level: intermediate Audience: advanced users (aka junk hunters)
This page (originally a book) is a collection of switch settings of various PC-98 expansion boards. It's a must for those who are hunting cheap junk boards.
PC-98 product database provided by NEC.
Brief history of PC-98 series.
Latest news about PC-98.
This page outlines PC-98, especially its differences from PC/AT, and offers support for oversea PC-98 developers.
Unofficial WWW pages by one of implementors who has been porting FreeBSD, NetBSD and XFree86 to PC-98.
Brief but high-level FAQ list by a knowledgeable PC-98 user.
Newsgroups for PC-98.
Copyright (C) 1998 ITO Takayuki, All rights reserved.