[fpc-pascal] DOS compiler wiki page: please review

greim greim at schleibinger.com
Thu Oct 10 18:23:34 CEST 2013

Am 06.10.2013 22:37, schrieb Nikolay Nikolov:
> On 10/05/2013 03:07 PM, greim wrote:
>> Hi,
>> writing a 8086 version of fpc is not so strange as some may think!
>> There are still some 80186 processors around running in embedded
>> systems! These architecture is certified for some applications in
>> industrial and avionik controll.
>> ....
>> So my wish list:
>> fpc for 80186, supporting the new extended addressing and writing the
>> header files for RTOS (see
>> http://www.beck-ipc.com/en/products/rtos/index.asp) incl. a FPU
>> emulation !
>  From what I read from the links you posted, the extended addressing
> seems to be just like the regular real mode, except that segments are
> spaced not 16, but 256 bytes apart, is that correct?

As far as i personally understand, yes.

If that's the case,
> it should be easy to support - it's just a matter of writing the RTL for
> the new OS and using the appropriate linker.

RTOS is a pimped IBM/MS-DOS. So standard functions like file i/o etc. 
are identical. Most of the DOS programs are running also on RTOS.

  FPC for i8086 produces
> object files in the standard ROMF file format, they just use the
> extension .o, instead of .obj. Note that FPC currently only supports the
> tiny, small and medium memory models. Compact, large and huge are
> planned, but not started yet. But you can try writing an RTL for RTOS
> with the current memory models. In principle, it shouldn't be any harder
> than porting the compiler to any new OS, where the CPU is already
> supported.

Maybe its enough to modify the linker for this special 80186, without 
touching the 8086 compiler?
This was not possible for the Borland compiler, because there are no 
.obj files.

  And when I implement the compact/large/huge memory models,
> the RTOS RTL will have to be adapted to support them. Most likely, the
> far heap manager (which doesn't exist yet) will have to be adapted to
> support the different spacing between the segments. As for FPU
> emulation, it is also on my TODO list :)

First of all i will try to run a small "Hallo World" on the RTOS 24 bit 
machine !



> Nikolay
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