+Pascal became popular very quickly because the original compiler was designed to be very easy to [Port]. It was written in Pascal and compiled to [ByteCode]s, called ''P-Code''. All anyone had to do to get a Pascal compiler working on a new machine was to write the simple P-Code VirtualMachine for it -- they could hack the compiler around to generate proper MachineCode later. This meant that Pascal spread very quickly through the world's Universities. They soon began teaching in Pascal -- it was a very good language for demonstrating structured programming, a hot topic at the time. 

+Standard Pascal was a nice language with terrible limitations: Pascal programs could not open files by name, could barely handle strings and could only pass arrays of predetermined sizes to functions. BrianKernighan famously described Pascal's problems in [Why Pascal is Not My Favorite Programming Language |http://www.lysator.liu.se/c/bwk-on-pascal.html]. ( It has to be noted that NicolasWirth had already addressed most of Pascal's problems in his follow-up language [Modula2] ''before'' Kernighan wrote this paper, and in some places Kernighan seems to be just complaining that Pascal is not [C].) At any rate, these limitations meant that Pascal splintered into dialects as people hacked in missing features in incompatible ways. [C] did not have this problem, so it gradually took over from the Pascal dialects. 

+The online book [Pascal Implementation: A Book and Sources | http://www.cwi.nl/~steven/pascal/] walks you through the source code to the original Pascal compiler (implemented in Pascal as a RecursiveDescentParser) . It's educational to read just as an extended critique of a non-trivial program.