Free Pascal
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Free Pascal (aka FPK Pascal) is a 32 and 64 bit professional Pascal compiler. It is available for different processors: Intel x86, Amd64/x86 64, PowerPC, Sparc. The following operating systems are supported: Linux, FreeBSD, Mac OS X/Darwin, Mac OS classic, DOS, Windows, OS/2, Netware (libc and classic) and MorphOS.
It is free (as in beer), and provides some compatability for Turbo Pascal, Dephi, and Mac Pascal; as well as being standard compliant.