CP437

Code Page 437, commonly known as CP437, is the original character set used by IBM PC DOS and MS-DOS. It is an 8-bit single-byte encoding that preserves the standard ASCII characters in the 0x00–0x7F range, while the 0x80–0xFF range contains the extended characters used by the system. The extended portion includes letters with diacritics, miscellaneous symbols, and a large set of graphic characters.

Historically, CP437 was introduced with the first IBM PC in 1981 and became the de facto standard OEM code page for DOS. It supported text-mode rendering with box-drawing characters and other symbols, enabling simple user interfaces without bitmap fonts. It was widely used across software on IBM PCs and compatibles throughout the 1980s and into the 1990s.

Technical notes about CP437 include its role as an 8-bit encoding with a fixed mapping to Unicode in modern contexts. Although most modern systems use Unicode, CP437 remains relevant for compatibility, emulation, and retro computing. Fonts and terminal emulators that emulate DOS text mode typically provide glyphs for the CP437 set, including the graphic characters that form the visual elements of interface design in early software.

Legacy and impact: CP437 influenced later DOS code pages and the way text-mode graphics were designed in early PC software. While newer encodings such as Unicode have supplanted CP437 for general use, CP437 is still encountered in emulators, vintage software restorations, and certain embedded or constrained environments that emulate IBM PC text rendering.