Exercises of Low Level Programming with 8086 Assembly Lecture, implemented with Emu8086 and DOSBox.

In general, Emu8086 is easier to use, write code and test program. For macOS, since it does not have macOS support, Crossover or directly Wine could be used. But sometimes Emu8086 may not work properly since it just and emulator, remember to check final program in DOSBox.

DOSBox

Installation Windows

• Download and install DOSBox under C:\dosbox
• Extract files of dosbox_bin.zip into C:\dosbox\bin
• Open configuration file C:\dosbox\DOSBox <version> Options and add following configurations at the end of file;

Change paths according to your setup:

[autoexec]
mount c c:\dosbox
mount b c:\dosbox\bin
mount d c:\Users\creat\Documents\GitHub\8086-assembly
PATH=z:\;c:\;b:\;d:\;

d:
cd exe

Installation macOS

• Download and install DOSBox under Applications
• Extract files of dosbox_bin.zip into ~/dosbox
• Open configuration file ~/Library/Preferences/DOSBox <version> Preferences and add following configurations at the end of file;

Change paths according to your setup:

[autoexec]
mount b ~/dosbox
mount d ~/Projects/Personal/8086-assembly
PATH=z:\;b:\;d:\;

d:
cd exe

Compile

Inside DOSBox;

// this will create .obj file from .asm (and .lst if you want)
masm test.asm

// this will create .exe from .obj (and .map if you want)
link test.obj

// linking multiple .obj files;
link test.obj + test2.obj

// if program is in type of com
// this will convert .exe to .com
exe2com test.exe

Debug

Inside DOSBox;

debug test.exe

-r    show registers, flags and next step
-t    run single step
-g    run to offset
-g cs:1e
-d    dump memory 
-d ds:0
-u    unassembly
-u cs:1e
-e    enter data into memory
-e 100 8B 07
-u 100 (see the assembly code)

We can also run debugger without input exe. Then debugger will allocate a DS for us.

debug

-a    start typing assembly (Type ENTER to exit)
-u    unassemble
-u cs:100

Visit here for all available commands.