Turbo Pascal needs to create, read from and write to files. Few simple routins take care for this.

For each source file Turbo Pascal keeps a record with essential data like file handle, file name, current line number, current position, conditional compilation If level, etc.

This short procedure reads unit from file to symbol tables. If header is not valid it reports error.

This procedure creates space in heap for exe header and typed constants, creates exe file and positions it to the start of the code.

This procedure processes system functions SeekEoln, SeekEof, Eoln for text files and Eof for all files.