From QB64 Wiki
QB64 is a compiler (C++ emitter) with an editor (IDE) that strives for 100% Qbasic and QuickBasic 4.5 compatibility. Galleon is the author of QB64, he has worked hard on QB64 for a very long time to make it compatible with QuickBasic 4.5. Users are free to request features and suggestions on the workings of QB64 on the forum, also C++ code and BASIC code can be suggested to be implemented.
QB64 not only strives for 100% QB 4.5 compatibility but also strives to extend the capabilities of QBasic to fit modern needs without changing the BASIC philosophy. New statements often begin with _ to keep it compatible with old QB source.
One exception to this is the improved TIMER statement which differs from the original TIMER statement only by an accuracy parameter (which does not change compatibility). Other enhancements are the use of full system memory, TCP/IP support, load/play soundfiles and to load/save image files, Absolute and Interrupt calls are built into QB64, no Libraries or Include files are necessary for those abilities.
Currently the QB64 community is fairly active in the developement of QB documentation (this wiki), bug reports, ideas, samples and helping beginners in the QB64 forum (http://www.qb64.net), also the community helps Galleon solve problems with the QB64 compiler and suggests ways to add compatibility.
As the name implies QB64 works on 64-bit systems, but 64-bit addressing is not implemented yet and is as such still 32-bit. Galleon says this will be easy to implement however and is expected to be implemented later this year. As of version 0.90 QB64 works on 64-bit linux systems.
QB64 is originally made in QB 4.5 and is self-compiled, this was the solution to the QB 4.5 and later QBX's memory problems, as of version 0.872 the source code .bas file is released! If you are good at programming you can add features yourself and suggest them to Galleon on the forums which will consider implementing the changes in the upcoming releases!
Galleon and the Community hope that you will have fun programming in QB64! If you need help just ask! Somebody will answer.
The QB64 Community