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Private company

Tenberry Software

Phoenix software company, developer of DOS/4GW and DOS/4G protected-mode extenders

Tenberry Software, formerly Rational Systems, was a software company based in Phoenix, Arizona, best known for developing DOS/4G and DOS/4GW, DOS extenders that became a de facto standard for running 32-bit software under 16-bit MS-DOS in the early 1990s. The company also developed DOS/16M, an earlier extender that enabled 16-bit applications to access extended memory beyond the conventional 640 KB limit.2 Wikipedia text CC BY-SA 4.0

Last updated Oct 21, 2026.

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Tenberry Software, formerly Rational Systems, was a software company based in Phoenix, Arizona, best known for developing DOS/4G and DOS/4GW, DOS extenders that became a de facto standard for running 32-bit software under 16-bit MS-DOS in the early 1990s. The company also developed DOS/16M, an earlier extender that enabled 16-bit applications to access extended memory beyond the conventional 640 KB limit.2

Sources

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