Updated: 12/29/2005
SWDev-Pascal
Compas , 280kb
Educational compiler. ComPas is not traditional tool to translate Pascal programs - it's an educational compiler. The main purpose of this software is to show how compiler works - what is variable, how different types of cycle are realized and so on. The results of translation can be seen on the display screen as a set of demonstrative tables with easy navigation. Compiler can make two types of codes - for special educational processor E97 and Intel code. Don't be afraid of complexity - ComPas is easy! In ZDNet Software Library ComPas had more than 8000 downloads." [Report a dead link]
http://downloads-zdnet.com.com/3000-2051-8184647. html?tag=lst-0-1

Dev Pascal
Free pascal compiler and windows IDE. Supports several pascal modes. [Report a dead link]
http://www.bloodshed.net

Dj Delorie's Pascal Compiler
[Report a dead link]
http://pascal-central.com/pc-tools/djcompiler.zip

Freepascal
Supports most of Turbo Pascal, some Delphi classes, and more. For DOS, Windows, Linux, more. This version has a problem with reading keyboard input, like function keys, cursor keys. Letters work ok. For a nice, free GUI lib for FPC try MOS. [Report a dead link]
http://www.freepascal.org

Gnu Pascal
For MSDOS, requires DJGPP, Mingw32, or Cygwin. Can be tricky to install for MSDOS. Supports ISO Pascal and Turbo Pascal. [Report a dead link]
http://www.gnu.org/directory/devel/compilers/GNUPascal.html

Pascal Reference
10 chapter free ebook on Turbo Pascal. [Report a dead link]
http://www.programmersheaven.com/search/Download. asp?FileID=3916

TMT Pascal
Pascal compiler. [Report a dead link]
http://www.tmt.com/download.htm

Turbo Pascal 3.02
Borland's free TP. [Report a dead link]
http://community.borland.com/article/0,1410,20792,00.html

Turbo Pascal 5.5
This link also has links to TP 5.5 OOP Guide. Also at http://community.borland.com/article/images/20803/tp55.zip. [Report a dead link]
http://community.borland.com/article/0,1410,20803,00.html

Turbo Pascal 7.0 for DOS
Seems to be missing some units. Also at http://byoge.tripod.com/turbo.htm and http://www.geocities.com/siliconvalley/horizon/2942/turbo.zip and http://www.geocities.com/siliconvalley/horizon/2942/fulltp.zip [Report a dead link]
http://www.simonhuggins.com/courses/progbegin/pascal/ download/

Virtual Pascal
Pascal compiler. It is compatibile with Borland Pascal and Delphi, including the Run-Time Library (RTL), an optimizing compiler, a powerful integrated debugger, and comprehensive online documentation. [Report a dead link]
http://www.vpascal.com

Visible Pascal
Pascal compiler [Report a dead link]
http://pascal-central.com/pc-tools/vispascal.zip