Insight Debugger for DOS



Insight is a simple real-mode DOS debugger written 100% in assembly language (Turbo Assembler). It binary is less than 30KB in size and uses only about 45KB RAM when running. Insight has disassembler (CPUs up to i486 are supported) and 8086/8088 built-in assembler. Insight can run resident in memory and invoked with shortcut key.

Insight was originally written by Victor Gamayunov as a hobby project in 1993-1994 and later improved and modified by him and Sergey Pimenov (till 1997). In March 1997 authors decided to make binaries for version 1.0 available to everyone and published them in FIDOnet conference as well as dedicated Internet page.

In 2002 Victor and Sergey agreed (a bit late) that debugger sources have to be open and released complete Insight 1.10 source code under GNU Public License v.2 (GPL2) on Jan 26, 2002. Later Insight sources we placed at FreeDOS web site.

In 2006 Oleg Chukaev and Dmitry Vodyannikov took Insight sources and started to improve them. You can find the most recent version on Insight at (see Download section below).


The primary debugger features
  • Step-by-step execution with step-in and step through supported
  • Built-in i486 disassembler and 8086/88 assembler
  • 16- and 32-bit registers display
  • User-friendly interface
  • Simple color highlight
  • Advanced code and data navigation with hotkeys
  • Code and data search
  • Can stay resident in memory
  • Binary less then 30KB, about 45KB in RAM
  • Written in 100% assembler (TASM)
  • Screenshots

    The Main Insight Window

    Context menu for Code Window

    About Window

    Context menu for Registers Window


    The first version of Insight Debugger released under GPL2 is 1.10. You can download it from this web site (see links below). The most recent version can be found at (

    Insight 1.10, binary and complete source code

    Insight 1.01 (1.0 bug fix), binary only

    Insight 1.0, binary only