Original sentence: FreeBASIC is an open-source 32-bit BASIC compiler available free of charge, with the syntax similar to that of QuickBASIC.Several commercial compilers were developed including PowerBasic, and Xbasic, with varying degrees of compatibility.Several open source and freeware BASIC compilers have also been developed
Edited sentence: As the name suggests FreeBASIC is an open-source 32-bit BASIC compiler available free of charge, with the syntax similar to that of QuickBASIC.However, its backwards compatibility is unsatisfactory, so several commercial compilers were developed including PowerBasic, and Xbasic, with varying degrees of compatibility.Several open source and freeware options exist or have existed, and one that shows good compatibility with QuickBASIC is FreeBASIC