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TSR vs DEVICE= (Announce)

posted by Ninho E-mail, 20.06.2010, 17:34

> > This might be true for some old DOS versions.
>
> My reference source for this is "DOS Programmers Reference", second
> edition, by Terry Dettmann, published in 1989. It claims to be accurate
> through MS-DOS 4.0, the latest version of DOS at the time the book was
> written. Given what I know about Microsoft, that's probably not something
> they would have changed in later versions of MS-DOS. ...
Never believe what your read (even in print, even if the source is MS - indeed, especially not if the source is Microsoft, or paraphrased from MS like so many bad textbooks !

In fact, starting with DOS 2.0 (where DOS device drivers and config.sys were introduced), the DOS int 21h API is loaded and (almost) properly initialised before the drivers in Config.sys are processed. Despite what MS ever said, all int 21h functions should be available.

With two caveats : - first, some functions make little to no sense in the context of loading drivers and shouldn't (normally) be used - but see WRAPPER.SYS for how one can arrange to run DOS programs from a driver without virtually any limits.

- secondly, there have been bugs in every versions of MS-DOS (cf. the "almost" in the above paragraph) which make some functions not work, unless one works around the bugs. See also discussions of my own "fixwrap.sys" in this forum.

---
Ninho

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