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Revision as of 12:14, 27 September 2013 by Nickysn (talk | contribs) (→‎Limitations)
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A DOS (8086) cross compiler is currently being developed in FPC trunk (the development version). It started as a hobby project meant to explore how to port FPC to a new platform.

The amount of (FPC on) DOS users is probably quite low, especially since there is an FPC compiler for the more capable GO32v2 DOS extender available which runs on 80386+ processors.


The compiler has not yet been enabled as a CPU/OS target in FPC.exe.

Please update/extend this page as more details become available.


The compiler is a cross compiler that runs at least on Windows (both x86 and x64) and Linux. For compiling, it needs:

  • the Netwide Assembler - NASM
  • the Open Watcom linker - WLINK
  • the Open Watcom library manager - WLIB

In theory it should be able to run on any platform, supported by FPC, where NASM and the Open Watcom tools are available. This includes DOS via the GO32V2 extender. However, because the Watcom tools for DOS are compiled with a different extender, there are some issues related to long file names and the passing of long command line arguments. This might be resolved by recompiling the Watcom tools with DJGPP or by implementing a 16-bit DOS backend asm object writer and linker inside FPC.


The DOS platforms brings some limitations, like

  • no simple way of pre-emptive multitasking.
  • it is unlikely the Lazarus LCL GUI will be ported to the DOS environment
    • However, an OpenGEM widget set is possible
    • When the large memory model of the i8086 code generator matures, Win16 support can also be implemented