I plan to use Pascal and assembly to write the operating system.

[Akiko_Official]

How can I compile pas code so that it does not rely on the runtime of the system but only on the runtime interrupts provided by the BIOS?

[Fibonacci]

Take a look at here
https://forum.lazarus.freepascal.org/index.php?topic=57787.0

[Akiko_Official]

Thank you, but the example it provides is -Tlinux, and I need to compile it into binary format - I need it on the boot block of my customized file system, which is why I cannot use any other Bootloader

[ccrause]

Take a look at here
https://forum.lazarus.freepascal.org/index.php?topic=57787.0

Please note the following comment in the above discussion by PascalDragon:

That article essentially abuses the Linux target for this. However for barebones development FPC has the Embedded target (most might associate it with micro controllers, but in essence it means “without an OS”).

There is an i386 embedded target that sets up a multiboot header then jumps to PASCALMAIN.  This may be a feasible starting point, basically all other functionality you have to provide yourself.

[Akiko_Official]

I'm sorry, it cannot use multiboot. Beacuse the bootloader(using assembly and pascal) is combined into the FS's boot block, it must compiled in binary format

[Laksen]

Read up on how to use objcopy. It can do what you need after compiling with -Tembedded

[Laksen]

Ah and missed that you wrote about interrupts.. For those you need to be in realmode where you'll need a 16 bit compiler.
I guess it might be possible theoretically to do with FPC but never tried it.

[Akiko_Official]

Thanks, could you tell me how it works?

Read up on how to use objcopy. It can do what you need after compiling with -Tembedded

[Leledumbo]

For those you need to be in realmode where you'll need a 16 bit compiler.

There's a 16-bit DOS (8086) cross compiler, I've tested in the past and it worked OK. You even have multiple memory models to choose.

[PascalDragon]

Ah and missed that you wrote about interrupts.. For those you need to be in realmode where you'll need a 16 bit compiler.
I guess it might be possible theoretically to do with FPC but never tried it.

It's possible with the i8086-embedded target however one needs to write custom startup code for it. I have done that once for something at work, but I have not yet found the time to document it.

[MarkMLl]

In any event, if doing something like this you have to be 100% confident that the start of the binary is in a format that the loader can handle. It's very common for this operation to be handled by the linker (which is OS-specific, or at least has command-line options to tailor it to a particular OS), and it's very common for it to derive from RTL initialisation code handcrafted in assembler: hence somebody's mention of objcopy to tune this.

When I was doing this sort of thing I had a custom binder program which put descriptor tables at the start of the binary. Input syntax was based on Intel documents, the implementation was my own.

I'd mention here that there used to be a mainframe range which was very heavily promoted as having all system software (i.e. including the OS) written in ALGOL. However when one scratched the surface one found that the OS had a special compiler distinct from that used for application code, and that the initial loader was a carefully-constructed binary: whether there was, in fact, an internal-use assembler is lost in the mists of time.

MarkMLl

[coradi]

nice,  can you provide some information and the progress?

For which CPU?

Why not Z80? :-) There is only CP/M at this moment

[PascalDragon]

Why not Z80? :-) There is only CP/M at this moment

So you don't know MSX-DOS, whatever the ZX Spectrum uses or SymbOS?

[coradi]

OK, yes. I forget the Others.
But now WE can have one in Pascal🤗 with Sourcecode.
Maybe there is a bigger Community für this diy z80 PCs

[marcov]

So you don't know MSX-DOS, whatever the ZX Spectrum uses or SymbOS?

C=128 in native mode ? :-)