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Last update: 14-October-2023: Added extra info. Some general improvements. Cleanup.
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The PC-98 is or was a series of Japanese Desktop computers almost IBM-Compatible developed by NEC in the 80s and 90s.
This means that the users can handle these computers as an IBM PC of the era, but a large number of software designed for them is not compatible with IBM computers, and vice versa.
The very first PC-98 model, the "PC-9801" (10.5 Kb, PNG, 736x736)
The PC-98 was really big in Japan, as big as being the undisputed home and business computer series in Japan during those years, until Wintel PCs started to penetrate the Japanese market.
Not being IBM compatible means that Japanese users didn't have access to most of the western software such as word processors, spreadsheet, games, etc. But fortunately for them, a certain number of these programs were ported or simply versioned to the platform, but also the PC-98 scene was very strong in Japan. You can virtually find a Japanese alternative to basically any software that you might need. So, you might not find Lotus Write, but you have Ichitaro, a word processing software tailored made in Japan for the Japanese market.
Needless to say that the PC-98 series was a huge hit in Japan and NEC completely dominated the whole personal and industrial computer market.
The PC-98 line of computers includes the PC-9801 and the PC-9821, both with similar architectures and *mostly* compatible with each other, but some differences that will be described later, and being the PC-9821 the evolution of the PC-9801.
PC-9821V200, one of the latest and most advanced models (20.7 Kb, PNG, 800x800)
The PC-98 is the natural evolution of the PC-8000 line of computers, and these were born from the PC-6000 series, and for that reason several features present in these older computers are also available in the PC-98, and being one of the most interesting one, the built-in Microsoft BASIC programming system.
When starting your PC-98, there is the possibility to boot from (floppy) disk or boot into BASIC prompt. Yes, the same OS is present in the VIC-20, the Commodore 64, the ZX Spectrum and virtually all the computers of the 70s and 80s. But interestingly enough, the PC-98 is not a "BASIC" computer, but an IBM-esque PC! Imagine your Compaq Deskpro coming with BASIC built-in. Wouldn't that be fantastic?
By default, the PC-98 will try to boot from the disk. If no OS is present, it will simply ask you to insert a system disk.
If you want to boot into BASIC, you will have to change the settings from the BIOS.
The built-in BIOS that is present in the computer ROM is a fairly standard Microsoft BASIC. It is important to note that even if your PC-98 comes with internal and external Floppy and Hard Disk capabilities, the default BASIC version is NOT a Disk-BASIC version, so you need to insert a system disk to be able to access the floppy drive.
Early PC-98s, and especially many of the 9801 models, the "BIOS" settings are called the DIP SWITCH configuration. When you turn on your PC-9821 (not PC-9801) after a long sleep without a backup battery, it will either boot up using default settings or it will ask you to "SET THE DIP SWITCH", meaning "please configure the BIOS settings". The computer will boot up with default settings even if you don't change anything.
As the name suggests, these settings are configured using DIP switches that can be easily accessed directly at the front or rear of the computer.
Although certain models of PC-98 show a small legend of what each DIP switch does, most of them do not show anything, so it would be impossible to configure the BIOS by trial and error. In fact, many PC-98 models can output video in various frequencies and screen sizes, so if your computer doesn't show any video, it is possible that it is not correctly configured for your display. This can be changed from the BIOS settings, but without a proper guide you might be thinking that the computer is faulty.
24 KHz is the default video output frequency, and not every monitor can decypher such frequency.
Fortunately for us, there is a very useful DIP SWITCH settings guide online that will help you figure out the best configuration for your needs. You can access this guide in the link below:
PC-9801 DIP Switch guide in Japanese (HTTP)
As you can see in the website above only DIP switch configurations for PC-9801 models are shown. This is because most, if not all, of the PC-9821 models already had a "visual" BIOS from which you can easily configure all the settings. The downside of this "visual" BIOS is that whenever the computer is turned off, the settings will be reset unless you use a backup battery.
Another downside is that if your PC-9821 is outputting 24 KHz by default, you cannot change that by a single physical switch. In this case, you can hold [GRPH] + [2] and turn on the computer. That will force it to start into 31 KHz mode.
Additionally, pressing [GRPH] + [1] will boot into 24 KHz.
Please note that the keys MUST be hold **BEFORE** turning on the computer. If you turn on the computer and immediately press the keys, it will not work!
Not every PC-98 supports this, so be aware of this thing if you ever want to acquire a PC-98.
Another useful key combination is [SHIFT] + [GRPH] + [RESET]. That will bring all the BIOS settings to factory defaults.
And finally, holding the [HELP] button will access the BIOS itself, that, lucky you, is fully in Japanese!
To summarise general key combinations when turning on the computer:
[HELP] : Will display the BIOS Settings (only on PC-98 models with graphical BIOS) [SHIFT] + [GRPH] + [RESET] : Factory Reset all BIOS settings (only on PC-98 models with graphical BIOS) [GRPH] + [1] : Boot up in 24 KHz video mode (not all models support this) [GRPH] + [2] : Boot up in 31 KHz video mode (not all models support this)
For those having a PC-9821, you may refer to the next pictures as a reference to configure your BIOS, with English translations:
BIOS Main Screen (25.5 Kb, PNG, 800x357)
BIOS General Settings (14.5 Kb, PNG, 768x515)
BIOS DIP Setting #1 (14.1 Kb, PNG, 768x515)
BIOS DIP Setting #2 (20.4 Kb, PNG, 768x515)
BIOS DIP Setting #3 (21.3 Kb, PNG, 768x515)
Power Saving (8.70 Kb, PNG, 768x515)
BIOS I/O Settings (13.4 Kb, PNG, 768x515)
You can use the arrow keys and [ENTER] key to navigate and change the settings.
Pressing [ESC] will bring you back to the main screen or exit the BIOS (if you are in the main screen).
Pressing the [HOME/CLR] key will factory reset the setting (similar to [SHIFT] + [GRPH] + [RESET], but from within the BIOS).
It is important to note that depending on the computer model, the graphical BIOS might look a bit different. Use the images above as a reference.
To summarise general key combinations from within the BIOS screen:
[ARROW KEYS] : Move Cursor [ENTER] : Accept [ESC] : Back / Exit BIOS [HOME/CLR] : Reset all setting to factory defaults
This graphical mode is the only available way to configure the BIOS in most PC-9821 models.
One feature that PC-98 did better than the IBM PCs was in the graphics realm. By default, IBM PCs in the early 80s shipped with a CGA or MDA graphics card, but because Japanese language uses ideograms, pretty much like Chinese, computers were required to have a resolution high enough to display all the tiny strokes.
While in the west users were enjoying 16 fixed colours from one of the limited available palettes and resolutions of 640x200, PC-98 users had 8 or 16 colours (depending on the model) freely taken from a palette of 4096 different colours and resolutions of 640x480, and that already from the first models in 1982, year where the first PC-98 was released.
Comparing EGA/CGA with "standard" PC-98 game graphics:
Typical game with EGA/CGA graphics in the 80s (60 Kb, PNG, 800x500)
Typical game with PC-98 graphics in the 80s (40.3 Kb, PNG, 800x340)
Although the images above have been dithered to reduce the file size, still, the abysmal difference can be clearly seen. And we are talking about the early to mid 80s! Graphics in western PCs will still require several years to come even close to PC-98 graphics quality, once VGA became finally available in 1987.
In either case, the original PC-98 comes originally with 2 display processors: one for text and another for graphics. This controllers, called the GDC (Graphics Display Controller), are two NEC 7220 chips. There is plenty of information about them online, so we will nto enter in details here.
If you are interested, you can read more about it in Gopherpedia.
The 7220 is a quite fast graphics processor, but due to the way PC-98s are designed, the computer doesn't take full advantage of the capabilities of the GDCs for gaming.
In most of the PC-98s the GDC clock speed can be configured to 5 MHz or 3.5MHz. For older games, it is recommended to set it to 3.5 MHz for better compatibility.
The GDC is the default and the most commonly used graphics processor, but there is also available in cetain PC-98s what is called the Graphics Charger (GRCG for short). This new chip improves the memory access capabilities, but only a couple of games make use of this chip, as most of the games use the GDC.
In addition to these two processors, some models of PC-98 also come with a blittle processor called Enhanced Graphics Charger, or EGC.
and to conclude with the graphic processing units, NEC designed a specialised 2D Graphics Card called "Window Accelerator". You can find them quite easily under the brand of various manufacturers and/or distributors. Unfortunately, these cards are barelly used in any game, or at least I've never seen any game making use of if, but if your environment is Windows 95 and you use mostly Windows 95 software, this card will definitely help with the Windows GUI, but if you are planning to use MS-DOS, the Window Accelerator will be mostly useless.
As for the video output, a variety of interfaces or connectors are available for the user, depending on the model.
Typical video output connectors are:
Typical I/O Ports in a PC-9801, such as the VX or VM (15Kb, PNG, 748x450)
(Detailed images of the ports in the "I/O and expandability" section)
(Coming soon)
Ichitaro, a word famous Word processor in MS-DOS: (10.9 Kb, PNG, 640x400)
