Differences between SBCS OS/2 and DBCS OS/2

┌──────────────────────────────────────────────────────────────────────┐
│DBCS OS/2 is a common name for OS/2 NLVs (National Language Version)  │
│that IBM provides to the Asia Pacific countries requiring the DBCS    │
│character set. In general, DBCS OS/2 is released following the        │
│release-up of SBCS OS/2.                                              │
└──────────────────────────────────────────────────────────────────────┘

OS/2 aims to be an international operating system, and its SBCS version has several provision as follows:

• DBCS environment vector

  DosQueryDBCSEnv(**) are used for your application program to determine whether the program is running on a SBCS code page or a combined code page. It retunes the DBCS environment vector of the current process code page to your program. If the program is running on a SBCS code page, the values of the vector are two bytes of zero. If it is running on a combined code page, the value shows the reserved areas for the first byte of DBCS at the current code page. See DBCS environmental vector to find the DBCS environment vector for each country.

• Mixed string support

  Most of APIs which accept character strings for their parameters can handle SBCS/DBCS mixed strings.

  Mixed strings can also be used for a file name, a directory name and a path name.

  All PM controls such as Buttons and List Boxes are DBCS-enabled.

SBCS OS/2 is the base of DBCS OS/2. Therefore, DBCS OS/2 inherits many things from SBCS OS/2. In addition, the following capabilities are given to DBCS OS/2 for DBCS support:

• PS/55 hardware(**) support

  DBCS OS/2 supports the IBM PS/55 and PS/V keyboards capable of inputting DBCS, both PS/55 and PS/V displays and printers capable of presenting DBCS.

• SBCS character support

  Though DBCS OS/2 is designed for DBCS languages, it supports not only DBCS but also SBCS. The SBCS code pages for DBCS OS/2 include alphanumeric characters and special symbols as well as SBCS code pages used on SBCS OS/2.

  The differences between an SBCS code page used on DBCS OS/2 and the one used on SBCS OS/2 are:

  • the former reserves code area for the first byte of DBCS characters.

  • the former includes unique phonetic characters used in DBCS language (in case of Japanese).

  • National use characters are assigned on 5CH and 7EH.
  For more details on the supported code pages on OS/2, refer to Supported code pages on OS/2 V2.1.

DBCS input method support

There are too many ideographic characters to assign to key-tops. This fact causes DBCS-unique mechanisms to convert SBCS into DBCS for inputting DBCS. For example, Kana to Kanji conversion method is a DBCS input method for Japanese. SBCS-DBCS conversion modules for DBCS input are a part of DBCS OS/2.

Although the conversion algorithm is different among Asian countries, the difference is hidden by PM to an application programs. The application receives the converted data as well as usual SBCS data so far as it uses PM functions.

Messages, menus, and dialog panels in Asian Languages

Messages, dialog panels, and menus of OS/2 are translated into Asian languages for better readability for Asian users.

Font

Fonts for combined code pages are added to SBCS fonts in order to present double-byte characters. In user's DBCS OS/2 environment, more than one raster fonts for combined code pages are, at least, installed. This is the only one fact you can assume at application programming. Do not assume anything on the fonts such as face names, various values of font sizes, or availability of out-line fonts.

DBCS OS/2 V2.1 provides proportional fonts for combined code pages and short vector outline fonts. Users can change the default System font to others, although they cannot do on SBCS OS/2 V2.1.