How to edit DOS program

February 12, 2019 at 06:52:04
Specs: Windows 10
we are using dos based PC program . it is running with sequence of instruction for testing . due to some internal problem we want to delete some instruction in the program so kindly help how to edit the program. What is source file extension so that i can check in my back up

thanks
Deiva


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#1
February 12, 2019 at 06:55:57
what is the file extention?

anyways you can probably try debug.exe to modify the file on a 32bit system

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#2
February 12, 2019 at 07:00:08
i opened the files in the hard disk found so many exe files amd MS DOS application named as command.com

message edited by dev_siga


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#3
February 12, 2019 at 07:15:06
.com files are written in plain text, open and modify them with notepad.exe or debug.exe (on 32/16bit systems only)

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Related Solutions

#4
February 12, 2019 at 07:18:47
if i edit in this file can i skip some steps during program execution

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#5
February 12, 2019 at 07:30:28
eeeh yeah, just insert 2 lines
where you want to jump to :mylabel:

goto :mylabel

and where you want the file to continue execution after goto :mylabel:

:mylabel

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#6
February 12, 2019 at 08:28:55
when i change any step in .com file how it will reflect in exe file
Whether i should change the .com file into exe after my modification???

message edited by dev_siga


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#7
February 12, 2019 at 08:53:58
hidde663 wrote:

> .com files are written in plain text, open and modify them with notepad.exe

What??????

No, that can't be what you meant. .com files are not plain text.
You must have been thinking of some other filetype. Were you
thinking of .sys or .bat, perhaps?

dev_siga mentioned command.com, which is a DOS program
that does many basic disk access functions such as reading directories,
copying, moving, and deleting files, displaying text files on the screen,
and starting other DOS programs. It is a binary file, not plain text.

I think you need to establish how much dev_siga understands
and exactly what he wants to do.

-- Jeff, in Minneapolis

message edited by Jeff Root


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#8
February 12, 2019 at 09:00:53
Unless something has changed in the last 40 years, .COM files are most certainly not text files. They're straight machine code files lacking any loader header, primarily targeting CP/M systems. To modify them, you would need a disassembler for 8-bit / 16-bit x86. If your problem .COM file is COMMAND.COM, it's probably corrupt, and you're better off finding an uncorrupted copy.

Maybe thinking of .CMD, the WinNT batch script extension?

How To Ask Questions The Smart Way

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#9
February 12, 2019 at 09:06:59
Thanks for your reply. I need one basic doubt tell me the source file extension so that with your help i will open that file and convert into exe and run the program

kindly help regarding this


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#10
February 12, 2019 at 09:29:06
One word of advice... Ensure you have an unedited/original version of any file you intend to edit; and have it somewhere safe from possible harm. That way if you screw up or whatever the copy you're playing with, editing... you can always make a fresh copy and start again.

"Never"simply play with the only copy of any given file. "Always" have a duplicate at least with which to play; and an original copy stored safe and secure - away from tweaks/changes at all times.


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#11
February 12, 2019 at 09:31:25
i am having multiply copy

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#12
February 12, 2019 at 09:46:18
Hi, dev_siga!

My knowledge of compiling and editing DOS programs is very limited,
so I hope that someone else who knows more will come along and
take over. But maybe I can get things started.

What is your first language? Knowing that could be helpful.

Clearly you know something about how programs work, but I can't
tell whether you know enough to be dangerous. Do you have any
programming background at all? Do you know any BASIC? Any
other programming language? Are you familiar with using DOS
batch file commands?

What program do you want to modify? Where did you obtain it?
How do you know that you want to delete an instruction from it?
What instruction do you want to delete?

The answers to those questions should take us a long way to
getting started.

-- Jeff, in Minneapolis


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#13
February 12, 2019 at 10:04:29
If you were to hunt for something like the old PC Tools or the Norton equivalent (can't recall what it was called) you can edit almost any dos file with that package. Likely there are copies out there on the web/eBay. I have the PC Tools set which I used occasionally way back when.

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#14
February 12, 2019 at 14:30:25
RE #7, yeah... got confused with .cmd, how stupid of me.

.com is on a whole different level

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