Hello,

I am trying to compile a very simple app (hello world kind) for DOS or even for the Windows 98 rescue disk.

My first attempts ended up with a "This program cannot be run in DOS mode".

On the FP IDE I see many targets, but I don´t know witch one to compile against. I see a few possible targets:

* GO32 V2 DOS extender
* Win32 for i386
* WDOSX DOS extender
* Watcom compatible DOS extenders

Witch one should I compile against?? Win32 doesn´t work and GO32 claims it can´t find system unit.

Should I recompile FPC for GO32 in order to use it? What is the difference between it and WDOX or Watcom??

One might wonder what the reason for compiling to DOS is? I happen to have an 486 running ibm-dos in my house and I´d like to use my own program to test the ISA Card I recently created, instead of the DEBUG program.

thanks,

Date sent: Tue, 8 Nov 2005 20:16:47 -0200
From: Felipe Monteiro de Carvalho
To: FPC-Pascal users discussions
Subject: [fpc-pascal] Compiling for DOS
Send reply to: FPC-Pascal users discussions

Hello,

Your best choice probably is GO32v2. However, as for any other target, you need RTL compiled for the given target, the appropriate binutils (as and ld) and the right configuration. If you can compile on a Win 9x/ME machine (or even machine with plain DOS), the easiest solution (not requiring you to play with configuration, proper setup of directories, etc.) is to download the old 1.0.10 version, make sure you don't have any other FPC version (Win32) in PATH and use that one. Alternatively you could overwrite that one with a 2.0.x snapshot (for GO32v2 target). There are other options too, but these might be more complex (I believe some of them were discussed in our GO32v2 forum).

If you encounter any difficulties, just ask.

Hopefully a DOS (GO32v2) version of FPC 2.x gets released with one of the next releases.

Tomas

Hi,

Your best choice probably is GO32v2. However, as for any other target, you need RTL compiled for the given target, the appropriate binutils (as and ld) and the right configuration.

Was FPC compiler able to create real-mode programs in the past? It would be very important for my use, a very precise osciloscope.

Can I still use interrupts and IN / OUT assembler opcodes in protected mode?

If you can compile on a Win 9x/ME machine (or even machine with plain DOS), the easiest solution (not requiring you to play with configuration, proper setup of directories, etc.) is to download the old 1.0.10 version

Thanks, I'll try that.

Hopefully a DOS (GO32v2) version of FPC 2.x gets released with one of the next releases.

Maybe I can help get it released. What is missing? Code or just someone that compiles the whole thing? I have access to a machine with IBM DOS.

thanks again,

Felipe, I use Win ME to make go32v2, v2.0.3 and v2.1.1 so this should work ok. I've also used win9se in the past.

I produce daily snapshots of these. See ftp.freepascal.org\ snapshots\v20 & v21, so you can download these & try them out.

Regards John

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Date sent: Sat, 12 Nov 2005 08:01:30 -0200
From: Felipe Monteiro de Carvalho
To: ,
FPC-Pascal users discussions
Subject: Re: [fpc-pascal] Compiling for DOS

Hi Felipe,

No, FPC was being created as a protected-mode compiler from the very beginning.

Can I still use interrupts and IN / OUT assembler opcodes in protected mode?

Yes, you can, although especially interrupts might be somewhat more complicated (depending on what you need to achieve).

For ports, you can use in/out instructions and the special array port[] as supported by TP/BP (requires adding unit ports to uses clause).

Regarding interrupts, there are (at least) two things to be aware of. First, there is one interrupt vector table for the protected mode and another table for the real mode. Calling "int xx" in your protected mode program calls the protected mode interrupt. This will work if interrupt handler for the protected mode version is installed - e.g. protected mode version of interrupt 21h, i.e. DOS services, is probably installed for most DPMI servers as far as I remember correctly, but the same doesn't have to be true for other interrupts. Calling the real mode version is possibly e.g. using GO32.RealIntr (or SysRealIntr).

Second, working with pointers/memory addresses is little bit more difficult. If you need to pass a memory block to some interrupt (e.g. a buffer to be filled with some information by the interrupt), you need to allocate this memory block within the first MB of your address space (real-mode code cannot access/address more), and you have to remember that this memory block is addressed different way while under real-mode (16-bit segment and offset must be passed to real-mode code) and when accessing it from protected-mode (32-bit flat address is used). Functions Global_Dos_Alloc and Global_Dos_Free provided in unit Go32 are your friends here.

Machine is not such a big problem (although our makefiles don't work under plain DOS, but require some LFN-capable system - it isn't a problem of the compiler, that one works under plain DOS without problems). There have been some bugs which prevented us from having version 2.0.0 released for GO32v2 target too. The most important issues should be hopefully fixed now, but some smaller ones still remain. Anybody able to help with debugging the remaining issues is certainly welcome. ;-)

Tomas

Hi,

No, FPC was being created as a protected-mode compiler from the very beginning.

Is it very different to compile for protect-mode DOS and real-mode DOS?

Interesting that FPC was based on TP 7, but TP 7 only compiled for real-mode.

Yes, you can, although especially interrupts might be somewhat more complicated (depending on what you need to achieve).

Let´s say write my own interrupt to communicate as fast as possible with a time sensitive hardware. I just wonder if a protected-mode could make this problematic....

Time sensitive hardware usually goes for real-mode solutions or very good drivers, or at least this is what I read.

For ports, you can use in/out instructions and the special array port[] as supported by TP/BP (requires adding unit ports to uses clause).

I am already using them at this time =) ... just on TP 7

As the main part of the program is a Lazarus project it would be nice to have Free Pascal compiling it.

Interesting. What is DPMI?

thanks for the hints,

John wrote

Felipe, I use Win ME to make go32v2, v2.0.3 and v2.1.1 so this should work ok. I've also used win9se in the past.

thanks, I´ll try them.

Yes. Real-mode Dos is generally 16 bit (although 32 bit real mode is possible as well, but that does not work as soon as emm386, qemm386 etc is used, or if you have a Dos box under any Windows flavour.

FPC does not contain a 80x86 16 bit code generator (nor a 32 bit Dos real mode RTL).

Interesting that FPC was based on TP 7, but TP 7 only compiled for real-mode.

Only the language was based on TP7. The code of the compiler and RTL was written from scratch. And the main reason to start FPC was because TP was only a 16 bit real mode compiler.

Jonas