Follow Slashdot stories on Twitter


Forgot your password?
Microsoft Operating Systems Software Windows

R.I.P. MS-DEBUG 1981 - 2009 240

AlphaZeta writes "After 28 years, MS-DEBUG is finally being phased out in Windows 7. Over the years, people have been using MS-DEBUG for writing code (virus/malware, you name it) and debugging. "
This discussion has been archived. No new comments can be posted.

R.I.P. MS-DEBUG 1981 - 2009

Comments Filter:
  • by just_another_sean ( 919159 ) on Friday May 08, 2009 @03:02PM (#27880219) Journal

    Wow, two comments and /.'ed already. Who knew MS-DEBUG had such power to make people want to actually RTFA!

  • by Anonymous Coward

    Is /. broken today?

  • by mikael ( 484 ) on Friday May 08, 2009 @03:05PM (#27880267)

    ... a new sourceforge project called Open-Debug is being created to replace it.

    • Re: (Score:2, Funny)

      by Anonymous Coward
      Isn't Win 7 supposed to ship with XP in a virtual machine? Just grab debug.exe from there.
  • OMG (Score:4, Funny)

    by Capt.DrumkenBum ( 1173011 ) on Friday May 08, 2009 @03:11PM (#27880363)
    They killed debug.
    You bastards!
  • by skeletor935 ( 790212 ) on Friday May 08, 2009 @03:11PM (#27880369) Journal
    Everyone confirming or denying the presence of MS-DEBUG on their windows machine, is confirming their use of windows, and getting their precious slashdot ID number increased by 50% and a free copy of Windows 7 because MS is tired of having to keep hosting Windows 98 SP 2 updates for every time you reformat
  • Sad day (Score:5, Interesting)

    by Masa ( 74401 ) on Friday May 08, 2009 @03:15PM (#27880441) Journal
    So much fond memories...

    The Debug.exe was actually my first contact to programming and the first language I learned, was x86 assembler.

    It was MS-DOS 2.xx and all my friends played with C64s and coded all kinds of cool things. My parents couldn't afford a C64 but they somehow got an old PC free. Demoscene was a new and hot thing in those days and me and my friend programmed our first demo completely using the Debug.exe. Merging the two code-bases was an interesting task, when all you had was two pieces of binary and some unused memory space for copy 'n' paste. The demo actually was quite cool. Unfortunately I have lost my only copy.
    • There was an excellent book where I came in contact with MS-DEBUG and which sparked my curiousity to explore assembly programming. DOS Power Tools (It was for version 5, if I can rememeber). Unfortunatelly I don't remember the author.
    • My parents couldn't afford a C64 but they somehow got an old PC free.

      That's really, really odd. C64s were always an order of magnitude cheaper than PCs. By 1983 C64s were maybe $300, while a PC with any decent accessories was well into the $3000 range.

      I'd say you got lucky, but the C64 was a better piece of kit anyway :P

      • by Bigbutt ( 65939 )

        It's not hard to do. I had a PC at home because I would bring it home from work (Leading Edge) and I had several a few years later, partly because a company I was working for went out of business taking my last two pay checks. I got two PCs and a Toshiba 1100+ laptop instead.


  • Debug (Score:5, Funny)

    by KingPin27 ( 1290730 ) on Friday May 08, 2009 @03:16PM (#27880453)
    Makes me wonder why Microsoft even created it in the first place..... not like THEY used it or anything.
  • by AaronW ( 33736 ) on Friday May 08, 2009 @03:16PM (#27880471) Homepage

    Back in the DOS 2.1 days when I got my first computer I didn't have any manuals. I quickly found debug, though, and saw all the strings in A bit later I actually used it for things like disassembling the boot sector and even writing some tiny programs via machine code since Microsoft's assembler and linker costs a fortune at the time and I was in junior high and beginning high school. I even used it to crack a number of programs via the disassembler command. There was also an improved version of debug I managed to get a hold of called symdeb.

    When I got the Borland (RIP) Turbo Assembler and their debugger I stopped using it.

    I haven't touched it in many years, especially since I moved away from Windows in the early 1990s, migrating first to OS/2 and later to Linux.

    • by mzs ( 595629 ) on Friday May 08, 2009 @04:52PM (#27881889)

      Here is another former TASM user piping up.

      I remember when I was kid (pre-TASM) and my dad got a blazing fast internal ISA 2400 baud modem (hee hee). But it would not work right in Windows 3.0, it worked fine in a DOS program. Back then you had to assign an IRQ and port. The internal cards used the same as COM1 and COM2, but it should have been okay. The ISR should have checked the first card and then chained to the next. But it simply was not working, we had a serial port mouse and the other serial port was used for a printer (the machine had two printers one for carbon copy forms the other a laser printer for letters on the parallel port).

      So after trying everything that I could think of I called MS support. Back then things were VERY different. The lady that answered spoke pacific NW English and was incredibly competent. She explained that some BIOSes were buggy and did not do the IRQ chaining correctly. We could not find an IRQ that was free that the modem card had a jumper for so she walked me over the phone commands to do in debug to patch a driver in Windows 3.0 to get around this issue. I was a freshman in high school at the time, that really left a mark on me. I had just learned how to use edlin before that. Soon after I got a copy of Turbo Pascal from this Polish guy I knew and I never looked back.

      Before then I had only done Basic and later TASM (no relation Turbo ASM, that is what the cartridge+floppy interface was called, probably Tandy ASM) programming on a CoCoII. But that few minutes in debug got me hooked on modern systems and led to C/C++ TASM by the time I finished high school. I got a summer job just so I could afford Borland C++, it was something like $400 (student discount, I could not sell programs I compiled), the printed manuals it came with were incredible. DOS, Windows, dBase, WP all had incredible printed manuals too. Man have times changed.

      Before TASM I sure did used debug a lot. It was a cheap assembler, disassembler (I needed to figure out some VGA routines from Borland), and you could use it a lot like you would dd on unix too.

      • Any suggestions on a good program and book to start into ASM these days? I've poked around some, but a lot of the ASM projects out there have either stalled or seem to expect some experience. I'm fine with either Linux or Windows as a platform.

        I kind of feel like I missed out on the golden age of assembly programming.

        • No one uses assembly any more, not on a desktop platform.

          Only place you'll find it is embedded device code or in special cases as inline code chunks within drivers, compilers, graphics code, etc., where you're trying to tweak the code to run "just so" because the compiler keeps building it "wrong" and you know this other way is better/faster/more correct.

        • by tjstork ( 137384 )

          I kind of feel like I missed out on the golden age of assembly programming.

          You did, because the hardware is so far removed from Assembly. But... assembly is still out there at least as a hobby on desktops.

        • NASM [] is still alive and kicking, it's latest release was about 3 days ago, there are plenty of tutorials [] and plenty of example code [] around to get you up to speed.

          Personally, my fav x86 assembly program was A86 [], i found it much easier to use that NASM.

      • by AaronW ( 33736 )

        I remember using it for things like that as well. I also remember my father got an EPROM programmer that was hard wired to use the same port as his graphics card and it was hard coded into the DOS program. A bit of work with a soldering iron changed the port but I had to go in via debug and patch the program to use the new port. I also used it back in the day to dump BIOS or to write to specific I/O ports and memory locations to experiment with different things.

  • Sad... (Score:5, Funny)

    by pablomme ( 1270790 ) on Friday May 08, 2009 @03:23PM (#27880561)

    I hope Mr. Debug gets over his loss soon.

  • so we don't need debug.exe anymore.

    Anyone remember Borland Turbo Debugger or Microsoft Codeview? I used to use them to debug programs as well in Assembly Language.

  • by sohp ( 22984 ) <> on Friday May 08, 2009 @03:31PM (#27880693) Homepage

    Using it to change this string in

    "Abort, Retry, Fail?"


    "Abhor, Retch, Fume!"

    Note that it fits in exactly the same number of bytes. That's important.

    • I've got Vista installed on a laptop. The UAC is sometimes killing me though, I'll switch it off later. But now that you let me remember that question, I can rest assured that it was at least MUCH better than that Abhor,Retch,Fume that seemed to do *exactly* the same no matter which one of the confusing options you took. Even now I don't understand the difference between Abhor and Fume.

      And no, I DON'T wanna know (some imbecile is going to explain anyway, but at least I tried).

      • Re: (Score:2, Funny)

        Well, "Abort" means you recognize that it's broken and are telling it to give up, this is what they did to DOS, which brought us Windows 95. In many ways, it was a lateral move.

        "Retry" means, yes, we admit it's broken, but we can do better. This was Windows NT.

        "Fail" == Vista

      • The real meaning...

        Retry is obvious. It trys again.

        Abort tells it to abort the operation - for example, if you're copying files, and there's a disk error, Abort will stop the copy altogether.

        Fail tells it to fail just that stage of the operation - for the copying files example, that sector or that file won't copy, but the rest of the copy operation will continue.

        And, you missed Ignore, which is a special version of fail - it tells it to use the erroneous data anyway.

  • feh (Score:5, Interesting)

    by ClintJCL ( 264898 ) <clintjcl+slashdot@ g m a i l . com> on Friday May 08, 2009 @03:34PM (#27880745) Homepage Journal
    bad move. debug.exe was the only way i could recover a harddrive that had a messed up partition table. No, neither fdisk nor the linux equivalent could fix it, not even with a full low-level format. only debug.exe. It was a damned weird situation. Linux lied and said it was fixed; Fdisk told the truth and said it couldn't fix it. Debug worked tho!!

    It's not like it hurts by sitting there on the harddrive, taking up a whopping 28K (or however big it is)....

    • Re:feh (Score:5, Informative)

      by Aranykai ( 1053846 ) <slgonser&gmail,com> on Friday May 08, 2009 @04:01PM (#27881123)

      Modern hard disks, as in anything made after 1994, should never be subjected to an LLF. The tracks and sectors are defined at the factory physically and you cannot change them. Now, what I think you mean to say is you 'reinitialized' or wrote zero's over the entire disk. Almost every disk manufacturer makes a utility to do this that you can download from their website. This ignores partitions, so it will fix a corrupted partition table.

    • Re:feh (Score:5, Informative)

      by PalmKiller ( 174161 ) on Friday May 08, 2009 @04:07PM (#27881211) Homepage

      In linux just use dd to write 512 zeros to /dev/hda (or /dev/sda or whatever the base drive is) for example

      dd bs=1 count=512 if=/dev/zero of=/dev/hda

      That will wipe the boot block clean, then you can use it like a brand new drive.

      Or if you want, just zero out the partition table using a seek=466 and a count=64 instead of the count=512

      • Mod parent up. This is a trivial way to blast away low level data that is bad, but good enough to fool disk utilities. I figured this one out on my own after fighting with a disk for a while.
      • Typo (Score:4, Informative)

        by PalmKiller ( 174161 ) on Friday May 08, 2009 @04:20PM (#27881421) Homepage
        Oops the seek=466 should have been 446 (or even 448 with a count of 62, either works)...just in case someone really wants to back up a partition table with nothing else.
    • Re: (Score:3, Interesting)

      by TheRaven64 ( 641858 )
      Wow, I'm glad I had Norton Utilities. It gave a nice hex editor view of files, or of regions of the disk. One of the fun things you could do with it was see how Elite savegames worked, and discover why copying them always failed. It turns out that Elite would write the data into a 512 byte sector and then truncate the file. The game data would still be on disk, but after where the OS thought the file ended. If you modified it in any editor, the entire disk block would be written back out and the bit of
  • by Anonymous Coward on Friday May 08, 2009 @03:41PM (#27880815)

    This article is entirely wrong. DEBUG.EXE hasn't been removed from Windows 7. It's just not included in 64-bit editions of Windows. That goes for 64-bit editions of Windows 2000, Windows XP, Windows Server 2003, Windows Vista, Windows Server 2008 and Windows 7. This is because the 16-bit emulator is no longer included in the 64-bit versions of Windows due to the fact that the x86-64 CPUs cannot switch to 16-bit mode. So it's not DEBUG.EXE that is gone, it's all of DOS that is gone.

    • by mzs ( 595629 ) on Friday May 08, 2009 @04:16PM (#27881357)

      "due to the fact that the x86-64 CPUs cannot switch to 16-bit mode."


      AMD64 CPUs most certainly support real mode. In fact that is how they boot, how else would you expect the VGA bios to execute during boot?

      They also support Virtual 8086 mode which you are confusing with 16-bit mode. The issue is that in Long mode (which is all that 64-bit MS OSs supprort) you cannot run in those modes. Instead you either run in 64-bit mode or compatibility mode (32-bit or 16-bit, no extra regs). MS certainly could have provided a way to switch between Long mode and Legacy mode but chose not to. Then when encountering a real mode program it would switch to Legacy mode. These switches are not cheap though, you'd likely have do things like quiesce DMA, and that is why MS decided to ditch it. In fact there was a similar issue with the 80286 and 16-bit protected mode, essentially a soft reset was needed to get back into real mode but that was done back then (with the advent of Windows 3.0) since so many programs would have been unusable otherwise.

  • by Datamonstar ( 845886 ) on Friday May 08, 2009 @03:43PM (#27880843)
    I'm such a poser that the only thing I used it for was low-level format of hard drives. But oh, how I'll miss it. I still remember being a phone tech and using the debug script for callers that I didn't like. I'd tell them "Okay, I'm going to tell you some commands and I'm not going to be able to stop so make sure you don't miss anything of else I'm not sure if I'll be able to recover your system ever again." And then I'd proceed to turbo-read the script without stopping. Ah, such fun.
  • Awwww.... (Score:4, Interesting)

    by feepness ( 543479 ) on Friday May 08, 2009 @03:54PM (#27880987) Homepage
    This was how I cracked Ultima V. They had a special sector on the floppy(!!) and read code off it, put it in the right place, and then ROT13ed that code.

    I traced through until I was past that point, added nops where the read/ROT13 was, and rewrote the exe. I thought I was a genius.

  • I remember having to use debug to format ESDI drives back in the day. They should keep it around - it's still a power tool. What, do they think there will be fewer people writing viruses if it is gone? As though there aren't alternatives out there?

  • DEBUG on the way out? Next they'll be trying to remove EDLIN? Where will it stop?

    (Bizarrely, the only time I have ever used EDLIN was to administer some dual-boot Linux / Windows NT boxes. I wrote a perl/Expect script that telnetted to each machine running Windows, used EDLIN to change boot.ini, and then ran 'shutdown -r'.)

  • Already gone... (Score:3, Interesting)

    by faragon ( 789704 ) on Friday May 08, 2009 @03:59PM (#27881085) Homepage
    ... for XP64 and Vista64.

    Here is my last tribute:

    C:\Users\faragon>copy con
    1 files copied.

    -a 100
    187E:0100 jmp 112
    187E:0102 db "Hello Slashdot!$"
    187E:0112 mov ah,9
    187E:0114 push cs
    187E:0115 pop ds
    187E:0116 mov dx,102
    187E:0119 int 21
    187E:011B int 20
    Writing 00048 bytes

    Hello Slashdot!
  • Every geek kid growing up in DOS knew how to give way too much money in SimCity using Debug. First time I ever pulled a 'cheat' off a network, either. I think I got that from Prodigy, though it might have been a real BBS.
  • by againjj ( 1132651 ) on Friday May 08, 2009 @04:28PM (#27881525)

    MS-DEBUG 1981 - 2009
    May 8, 2009, 11:16 am

    Earlier this week (May 5) Microsoft Windows 7 Release Candidate was released to the general public and like many technology enthusiasts I downloaded a copy early in the morning hours on Tuesday, shortly after Microsoft made it available on its website.

    The RC build of Windows 7 (build 7100) has many tweaks over the previous beta build I have (build 7000) and I have not yet played with it long enough to come up with any meaningful conclusions. However, this is not the point of this article. As you might have noticed from the title of this article, I was not about to talk about my experience with Windows 7 (maybe I will write about it later). What I noticed the first thing in Windows 7 is that the DEBUG command is nowhere to be found.

    I was just old enough to remember the very early days of DEBUG under MS-DOS. In fact, I was fascinated with such a small and yet powerful tool that came with every version of MS-DOS distribution. the DEBUG command was so powerful that you could do almost anything with your machine with sometimes just a few key strokes.

    For a long time, I used DEBUG to learn x86 assembly language and to learn about disk (both floppy disks and harddrives) structures and file systems. And occasionally, I would use DEBUG to edit binary files.

    I remembered that I could use commands like

    -l 100 0 0 1

    to load the boot sector from floppy A and inspect whether the boot sector was infected with any virus and if so, I would find a clean floppy disk and using DEBUG to write its boot sector to the disk that was infected.

    And routinely, I would use the following commands to inspect the partition table of my harddrive to make sure that it was free from any infections:

    mov ax, 0201
    mov bx, 1000
    mov cx, 0001
    mov dx, 0080
    int 13
    int 3
    -g 100
    -d 1000

    Remember this one?

    jmp ffff:0000

    I remembered that someone at my high school used to play the pranks by changing the very first few bytes on floppy disks to EA:00:00:FF and placed the disks in computers in the lab so that whenever someone turned on the computer, it would enter an infinite reboot cycle.

    And when CIH stroke in the late nineties, my friends and I would use DEBUG to inspect the virus's code to see how the instructions could actually be used to cause real physical damage to the hardware.

    After Windows came along, I still used DEBUG often. After all, deep inside Windows (up till Windows ME), there was MS-DOS and for years, user were allowed to operate in real mode if they so inclined to. With the advent of Windows 2000 and then later Windows XP people started to forget about DEBUG since the operating system became true 32bit and the DOS prompt became just an emulator. You could still view files and write assembly code within DEBUG, but it was in a protected environment and everything you do was pretty safe and you couldn't really do anything harmful to the hardware (of course, you could still overwrite sectors in floppy disks if you wanted to).

    Ah, those were the good old days. Just like QBasic disappeared from later versions MS-DOS, DEBUG has gradually become obsolete. It remained in Windows Vista, but it is no where to be found in Windows 7. At last, Windows has shed one of its last vintage applications from the MS-DOS era.

  • I cracked my first game using "debug" a long time ago... It was "Speedball II, Brutal Deluxe", which remains in the running for Best Video Game Title Ever.

    FWIW, I didn't do anything with the crack. It was my own legal copy of the game. I just wanted to see if I could do it. One little NOP, and the whole call to the copy protection subroutine was canceled. Ha!

  • Please observe a moment of silence for the last command you'll ever type in debug...

    f 0000:0000 ffff ff

  • "Over the years"...yeah? not over all twenty eight of them, surely! When did you last use debug? I probably haven't used it since 1989 for hacking command names in in MS-DOS 3.3.

  • by Tired and Emotional ( 750842 ) on Friday May 08, 2009 @06:07PM (#27882873)
    A colleague and I once edited a text startup file for windows using debug - config.sys probably but I don't remember for sure.

    We were at a trade show and needed to make a change to the file but edit, for some strange reason, was missing from the machine, so it was the only thing we had to make the edit.

    After that I made sure I always had a floppy with key tools with me.

  • by IvyKing ( 732111 ) on Saturday May 09, 2009 @12:15AM (#27885347)
    DEBUG was actually part of QDOS/86-DOS before MS thought about buying the rights from Seattle Computer Products. The DEBUG commands and syntax were similar to the features in the EPROM monitor that came with the SCP CPU's (actually on the CPU support card).
  • by Kaenneth ( 82978 ) on Saturday May 09, 2009 @12:16AM (#27885359) Homepage Journal

    Fixed some source code files that someone had mis-saved in Notepad as UTF-8, or such.

    the files had a Unicode Byte-Order-Mark character which the compiler choked on. FEFF the Zero-width, non-breaking space. It's literally an invisible character, so the easiest way to verify/fix the problem is a hex editor, so I used the always-handy DEBUG.

Houston, Tranquillity Base here. The Eagle has landed. -- Neil Armstrong