Notes on the Use of DOS Programs Under Windows

by Martin Clausen (mc AT rotgradpsi DOT de)

Since my programs are compiled using a DOS compiler, they have to run in a emulation under Windows. Direct hardware access disturbs the security architecture of Windows, since this might lead to collision between programs running at the same time. Therefore depending on the settings Windows might block this direct hardware access. The user does not have to expect this from Win 95, Win 98 and Win 98 SE. But for the Win NT-type of windows it is very likely. This includes Win 2000 and Win XP.

Win NT-Type Operating Systems

Use the mode with administrator rights and run the program portenabler prior to the dos application. This procedure, will initialize and than immediately deinitialize a temporary driver leaving the ports accessible for DOS programs.

A better solution seems to be a littel freeware program. The page is in Czech, but the idea can be unterstood or just download the file directly here.

Win 95, Win 98, Win 98 SE

If the DOS program "hangs" during an attempt to access the serial port, add the following entry to the [386Enh] section of the System.ini file:

Com<n>AutoAssign=0

Where <n> is the number of the com port.

See Microsoft knowledge base, article ID: Q130402

Disclaimer: No warranty at all!
Copyright by Martin Clausen, Germany.
Contact the author: mc AT rotgradpsi DOT de
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