Free Pascal compiler for 8051
Here you can find documentation on Turbo51 syntax, compiler switches and directives, features, internals and other useful information. Take a look also at some code examples (pascal source code and Turbo51 generated files) from which you can get an impression on how to write programs with Turbo51. If you are still missing something you can always ask for help.
If you are already familiar with 8051 assembly language programming you can start with Turbo51 as 8051 assembly language compiler (see assembler procedures) and then add some Pascal statements step by step until you become familiar with Turbo51 and Pascal syntax. A good approach is also to compile some Pascal code and then check generated code (ASM file). This way you can learn assembly language, get some ideas on how to write effective code and become familiar with the compiler.