An experimental fork of MS Kermit. Cross compiles for MS-DOS on modern GNU/Linux systems using no proprietary software. The executable is 16-bit (8086) and can run on original IBM PC hardware or in an emulator such as dosbox.
If you have jwasm and owcc installed (see below), then you can compile a DOS executable of KERMIT.EXE by simply running 'make' on your GNU/Linux box.
To compile, requires the jwasm assembler and Open Watcom C compiler (owcc).
I used tuxxi's masm-unix which made compiling jwasm on GNU/Linux straight forward.
Cut and paste this into a command line to compile and install jwasm:
sudo apt install build-essential cmake
git clone http://github.com/tuxxi/masm-unix
cd masm_unix/src/JWasm
cmake . && make && sudo cp -p jwasm /usr/local/bin/The Open Watcom v2 source code is overly large to download and git times out, so I had to install a prebuilt copy.
Cut and paste these commands to install the Open Watcom v2 C compiler:
cd
mkdir ow2
cd ow2
R=https://github.com/open-watcom/open-watcom-v2/releases
wget -O ow2.zip "$R"/download/Current-build/open-watcom-2_0-c-linux-x64
unzip ow2.zip
rm -r ow2.zip binnt binp binw rdos rh
mv binl64 bin
cd bin
chmod +x $(file * | grep ELF | cut -f1 -d:)
mv vi weevil32-bit binaries
Binaries are in binl instead of binl64; rename it to just bin.
If you don't have a binl directory, try changing x64 to x86 in the
wget line.
cd
mkdir ow2
cd ow2
R=https://github.com/open-watcom/open-watcom-v2/releases
wget -O ow2.zip "$R"/download/Current-build/open-watcom-2_0-c-linux-x86
unzip ow2.zip
rm -r ow2.zip binnt binp binw rdos rh
mv binl bin
cd bin
chmod +x $(file * | grep ELF | cut -f1 -d:)
mv vi weevilAbout weevil
Note that we've renamed the Watcom editor to weevil because calling
it vi on a UNIX system is silly. It is clearly the love-child of
Microsoft EDIT and ed plus it's a bit buggy (try Ctrl+C), thus
"weevil".
To use the Watcom C compiler, you'll need to setup the compilation environment like so:
export WATCOM=${HOME}/ow2
export PATH+=:${WATCOM}/bin
export INCLUDE=${WATCOM}/hYou can run that at the command line or add it to the Makefile.
owcc -bdos -mcmodel=s -o myprog.exe myprog.cYou can then execute the .exe file in dosbox to test it out.
-
Get it to compile under GNU/Linux
-
Test the .EXE on an IBM PC
-
Reduce file size so it is more useful on retro-PCs.
- Simple Methods
- Look into runtime DOS executable compressors. Do any exist
that are Free Software?
- Surprisingly, Yes!
- UPX can be installed with
apt install upx-ucl. - Running
upxon KERMIT.EXE cuts the size in half to 152 KB. - Noticeably slower start up time in emulation with DOSBOX.
- Compiler, linker flags.
- Investigate: why is Open Watcom executable 50 KB larger than the one created by Microsoft tools in 1999. Is it Watcom's standard library?
- Check how Open Watcom's PACKDATA works.
- Kermit 3.14 notes state that 40KB was saved by using PACKDATA option of LINK.EXE. That option exists in Open Watcom but produces no savings in file size.
- ** WARNING! ** I had thought PACKDATA was safe to experiment with, but I realized that since stack checking is disabled, a smaller segment size might cause pointers to wrap around!
- What is the max size of the data structures in Kermit?
- Look into runtime DOS executable compressors. Do any exist
that are Free Software?
- Complex Methods
- Conditional compilation
- Add "Lite" versions (no NET, no GRAPHICS, neither) to Makefile.
- What existing subsystems does CHECK command identify?
- IF: ???
- Network: How does this differ from TCP?
- TCP/IP:
- Graphics: Tek4010 & Sixel
- Terminal: Terminal emulation. no_terminal implies no_graphics.
- (nls_portuguese: Missing from check but exists as ifdef.)
- Identify other large subsystems
- serial port? script interpreter? H19 and other terms?
- weird networks like IPX
- Wrap them in #ifdef, same as Lite.
- Analyze algorithms and datastructures to trim for size.
- How large is Kermit's TCP/IP, DHCP, and DNS implementation? Is mTCP smaller?
- Conditional compilation
-
Maybe include the numerous miscellaneous supplementary files that came with the MS Kermit 3.14 distribution.
-
Bundle with FreeDOS as a bootable 360KB disk image.
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