This section describes the system hardware that are used in the DBCS countries. Basically, a DBCS system hardware is different from a SBCS system hardware in the keyboard, display and printer devices.
Note: In DBCS countries, the DBCS unique hardware were required to provide the DBCS functions. However, the current personal system hardware, and the DBCS system software have been improved so that the SBCS hardware have enough capability for the DBCS software, and the DBCS system software can support the SBCS hardware as well as the DBCS hardware. Currently, the DBCS hardware, PS/55 system unit and its peripheral devices, are not sold in the market of PRC. The OS/2 P support only the PS/2 and PS/VP system hardware.
PS/55 is known as the DBCS personal system hardware. The relation ship between PS/55 and IBM PS/2 could be described as close cousins. Both are built from the Intel 80286/80386/80486 family of microprocessors. The difference of them is that the PS/55 has a DBCS keyboard which has more keys than the keyboard of a PS/2. Besides the CGA, EGA, VGA and XGA that the PS/2 supports, the PS/55 supports also a DBCS unique display adapter card. The PS/55 high resolution adapter card, also called DA/2 (Display Adapter/2 card), has a built in ROM, which provides the DBCS font data for the DBCS system software. The font data of this ROM is called ROS font. The PS/55 printer also provides the built in ROS font and handles the PS/55 printer data stream.
As the personal system had been evolved from IBM-PC or PC XT to PC AT, PS/2 and PS/VP, the PS/55 also had been evolved from 5550 series to PS/55 series and PS/V.
The bus structure and adapters of PS/55 non-Micro Channel Architecture models are not compatible with PS/2 Micro Channel Architecture models, IBM PC or AT.
The recent IBM PS/55 models, which use Micro Channel Architecture and have a VGA on the system board are called Micro Channel Architecture models (or converged models). The Micro Channel Architecture models with a G-keyboard (a DBCS keyboard, compatible with IBM PS/2 Enhanced Keyboard) and a converged printer are compatible with the Micro Channel Architecture models of IBM PS/2, such as model 70 and 80. They support two modes of the display and printer operations, one for DBCS environment, the other for SBCS environment respectively. Therefore, you can install SBCS OS2 and IBM PC DOS onto the Micro Channel Architecture models; and many IBM PS/2 applications can be executed without modifications (but only for SBCS). In P.R.C., the PS/55 hardware are replaced by the PS/VP hardware. The DBCS system software for PRC do not even support the DA/2 of the PS/55, but only support the VGA, SVGA or XGA.
The PS/V system is a Japanese version of PS/Value Point system. They are different on some features that required by the local marketing. Most current DBCS system software can support the PS/V as well as the PS/VP.
OADG, Open Architecture Developers' Group (established by IBM Japan) defined a minimum system hardware specification for the DBCS system in Japan. The OADG hardware requires a PC AT compatible system board with a VGA or higher resolution display adapter and a DBCS keyboard. In other DBCS countries other than Japan, a similar hardware is required for the DBCS system software, the DBCS OS/2 and DOS.