Compiling a FOSSIL aware 16bit DOS executable with FPC

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Recently Captain Hood of Black Flag BBS asked if I could throw together a quick door that could run under Oblivion/2 for displaying ANSI scrollers in a semi slowed down fashion. You see, back in the day the speed you saw an ANSI render was essentially that of your modem – 9600bps for example.

So what the hell, why not do this in Pascal?! I downloaded Free Pascal, built the 8086-msdos cross compiler and punched in some code.

Here are the steps I took if anyone out there in the world needs to write a 8086 16bit DOS application in Pascal :)

Note that these instructions are from from a Elementary OS Freya x86_64 box. YMMV.

Prep work

Install dependencies

sudo apt-get install nasm subversion

FPC

To cross compile FPC, you will need FPC. I used the .dep from Lazarus on Sourceforge (You should only need fpc*2.6.4-**amd64.deb)

Build the 8086-msdos cross compiler

(This is covered more extensively in the FPC wiki)

  1. Checkout the FPC source from TRUNK:

    svn checkout http://svn.freepascal.org/svn/fpc/trunk fpc

  2. Build:

    make clean all OS_TARGET=msdos CPU_TARGET=i8086 OPT=”-CX -XXs” CROSSOPT=-WmSmall BINUTILSPREFIX= PP=/usr/bin/ppcx64

  3. Install:

    make crossinstall OS_SOURCE=linux CPU_SOURCE=i386 OS_TARGET=msdos CPU_TARGET=i8086 PP=compiler/ppcross8086 CROSSOPT=-WmSmall BINUTILSPREFIX= INSTALL_PREFIX=/home///fpc-i8086/snapshot/small OPT=”-CX -XXs”

Be sure to replace the value of INSTALL_PREFIX with an appropriate path!

1.
Repeat steps #2 & #3 replacing -WmSmall with the various models you wish: Medium, Large, etc. See the FPC wiki for details.

2.
Update your fpc.cfg file. The default location is /etc/fpc.cfg. Make the following changes:

Add: 

#ifdef cpui8086
-CX
-XX
-XP
#endif

Replace: 

-Fu/usr/lib/fpc/$fpcversion/units/$fpctarget
-Fu/usr/lib/fpc/$fpcversion/units/$fpctarget/*
-Fu/usr/lib/fpc/$fpcversion/units/$fpctarget/rtl

with: 

#IFDEF CPUI8086
-Fu/home/<user>/<where>/fpc-i8086/snapshot/$fpcmemorymodel/lib/fpc/$fpcversion/units/$fpctarget
-Fu/home/<user>/<where>/fpc-i8086/snapshot/$fpcmemorymodel/lib/fpc/$fpcversion/units/$fpctarget/*
-Fu/home/<user>/<where>/fpc-i8086/snapshot/$fpcmemorymodel/lib/fpc/$fpcversion/units/$fpctarget/rtl
#ELSE
-Fu/usr/lib/fpc/$fpcversion/units/$fpctarget
-Fu/usr/lib/fpc/$fpcversion/units/$fpctarget/*
-Fu/usr/lib/fpc/$fpcversion/units/$fpctarget/rtl
#ENDIF

FOSSIL support

There is a nice Pascal package for DOS FOSSIL support called Ele Communications Kit 1.2. You can find it on the BBS archive site. Search for ELECOM12.ZIP elsewhere.

I won’t get into the details of the library itself – there is an EXAMPLE.PAS that makes it fairly clear: Open a COM port that FOSSIL is bound to, do I/O, close it. Nothing fancy.

Compile!

After you have written yourself a nice little FOSSIL aware piece of source, compile as such:

fpc-i8086/ppcross8086 -WmHuge -Fu./ELEC/ SOURCE.PAS

Again, replace -WmHuge with the model of your choice. The cross compiler (ppcross8086) is found under the path you specified with INSTALL_PREFIX of course.

SLOWMO!

As for myself, I created something super simple called SLOWMO! It’s now released under Acidic modding for giggles:

img

Enjoy!