Two versions of TeX have been developed for the IBM PC (and compatibles): MicroTeX from Addison-Wesley and PCTeX froM Personal TeX. Two are also available for the Apple Macintosh TeXtures from Addison-Wesley and MacTex, developed by FTL Systems of Toronto.
It is useful to distinguish between an implementation of TeX (the installation of TeX in some specific computer environment, together with supplemental programs such as printer drivers) and the program TeX. The latter takes a source file (consisting of text and TeX commands) and produces a device-independent (DVI) file. This DVI file is an "ideal" description of what the typeset pages should look like, without any reference to a specific printer or phototypesetter.
The DVI file must then be further processed for printing or display on a screen, but this past-processing is not strictly speaking, part of the program TeX. Once the DVI file is complete, TeX's work is done.
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