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@totalspectrum totalspectrum released this Jan 20, 2020

FlexGUI is a simple IDE for programming the Parallax Propeller2 and/or Propeller1. It is a front end for the fastspin compiler, which can compile Spin, BASIC, PASM, or C code to Propeller 1 or 2 assembly language. The Spin and BASIC support is quite complete, and while the C support is a work in progress it works for many things. FlexGUI also includes a micropython interpreter and Lisp interpreter which you can try out.

To use it, download "" and then unpack it into a folder. Run flexgui.exe. The menus should be fairly self explanatory. The GUI will compile whatever file is on top when you click the "Compile" or "Compile & Run" button.

flexgui uses Dave Hein's loadp2 to load P2 binaries, and David Betz's proploader to load P1 binaries. Both are great tools, and many thanks to their authors!

This version supports the P2 Eval board (both old and new silicon), and has P2 as the default output platform (but you can change it to Propeller 1). It has some updated samples, and has the latest versions of fastspin (4.1.0) and loadp2 (0.39).

Thanks to the support of my patrons at we have a digital signing certificate, which should remove the Windows Authenticode warnings for flexgui. Thank you to everyone who has contributed, and if you find fastspin/flexgui useful please sign up as a patron to continue to support its development!

Notable changes since 4.1.0 are:

  • Mac binaries are now included in the binary release
  • Ability to write binaries to the SDCard on the P2-ES board
  • Option to automatically reload files changed outside the editor
  • Better help menus
  • The Spin language support has been updated to more closely track Chip's work. In particular, if you were using "pausems" in Spin change it to "waitms". Some other Spin2 intrinsics have changed name as well.
  • A huge number of additions to the BASIC language. Thanks to JRoark's contributions the string handling functions are much more complete, and we have new operators to make it more FreeBasic compatible. Some Spin2 features (such as multiple assignments and Spin2 intrinsics like WRPIN) are available in BASIC now as well.
  • Lots of bug fixes, particularly in the C compiler
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