Talk:COM file

message: I deleted the discussion of how the default path in UNIX helps prevent execution of maliciously named binaries in the current directory. While this is a similar problem, even if this were the case in MS-DOS it wouldn't fix the problem, since the COM file is usually placed in the same directory as the EXE file, in which case it would still find the COM file before the EXE file. It seems more appropriate for an article about paths and default search paths. Deco 19:21, 17 Apr 2005 (UTC)
thread_title:  Default path 

message: Would someone care to explain that? I am under the impression that a .COM file is just loaded to some segment as is and the operating system jumps to run it. I do not think that MS-DOS on PC has the ability of running fat .COM files, it is just so simple and dumb loading of the binary as possible. I do believe .EXE files can be fat binaries, since on Windows 3.11 the programs usually check if Windows is running or not, and there is many DOS device drivers which are .EXE files but still can be loaded like .SYS files, because the files have both properties of a program and a device driver structure implemented somehow. Those who know better can enlighten me.
:It isn't something done by the operating system; it's done by the COM file itself. The first few bytes have to be, simultaneously, valid x86 code and valid x80 code. For example, the utilities in the MYZ80 emulator start 0xEB 0x52 0xEB. An 8086 sees this as a jump and reads its next instruction from 0x0154; an 8080 goes straight through and reads its next instruction from 0x0103. A fully fat COM file would then include two copies of the rest of its code, one for CP/M and x80, and one for MS-DOS and x86. HungryHorace 11:43, 17 January 2006 (UTC)
replies: text: Is there any reference for this? Pol098 (talk) 13:17, 17 November 2011 (UTC)
thread_title:  Exactly how is a .COM binary a fat binary? 

message: The section on Execution preference and its subsection Malicious use are not totally related.  Execution preference contains an example of malicious use.  The malicious use listed under Malicious use (having a COM file resemble a URL) does not really relate to Execution preference.  I think this needs to be reorganized.  Agree/disagree?  
Arun Philip 16:59, 30 January 2006 (UTC)
thread_title:  Malicious Use and .COM vs .EXE 

message: There are no details on what the system puts in between 0x00 and 0xFF at program execution. It is reserved, but what does it contain? I have been told the command line parameters were stored in there somewhere. That information is seldom available on the internet tho.
--88.170.36.239 (talk) 11:01, 28 March 2008 (UTC)
replies: text: http://en.wikipedia.org/wiki/Program_Segment_Prefix  —Preceding unsigned comment added by 76.170.204.223 (talk) 05:53, 25 June 2008 (UTC)
thread_title:  Command line arguments and COM files 

message: Should we mention how little legitimate use there is for a .com file on a modern home computer, if any? We try to reassure people there's nothing dangerous about a .com files, but when's the last time you saw a legitimate .com file on a home computer? --12.196.11.130 (talk) 22:01, 19 July 2010 (UTC)
replies: text: I know that Visual Studio uses a .com file in order to allow the command "devenv" to correspond to a command line application despite the fact that devenv.exe is a windows application. --Kragen2uk (talk) 03:50, 4 February 2011 (UTC)

text: COMMAND.COM is still widely found on PCs. -- 213.105.186.124 (talk) 01:21, 10 July 2012 (UTC)
thread_title:  Legitimate use 

message: The article erroneously give the impression that the executable .COM extension is no longer valid on 64-bit Windows.
Someone might like to explain that this is not the case and why:
For example I have a BCBeCyPDFMetaEdit.com and WinSCP.com in my binaries directory that run under 64-bit Windows.
So these must be either valid Win32 or Win64 applications with a the file Properties->Details "Type" of "MS-DOS Application" even though they are not.
(They may well be WinXX Console EXEs with a COM extension that get loaded as a result of a .COM extension still existant in the PATHEXT on Win64.  If so or not someone might like to explain this.) 122.148.41.172 (talk) 02:05, 29 June 2012 (UTC)
replies: text: 11 years have passed and that impression is still present in the article. Funny thing, a  command that can be used in Command Prompt is in fact a... .COM file, still available in 64-bit Windows! 83.11.130.13 (talk) 15:35, 6 July 2023 (UTC)
thread_title:  Platform support 

message: I have never seen .com used as a virus.
LMGN  (talk) 17:29, 13 December 2015 (GMT)
:Most of these are .com files. --> https://www.wired.com/2013/10/15-awesome-looking-viruses-from-the-ms-dos-era/ MrZoolook (talk) 12:51, 14 January 2017 (UTC)
thread_title:  .com Isn't used for viruses. 

message: Raymond Chen has a nice blog post that explains a lot of the history and differences between COM and EXE files. He's clearly an authority on the topic but is this a reliable source, given that it's an "unofficial" blog post? https://blogs.msdn.microsoft.com/oldnewthing/20080324-00/?p=23033 GSMR (talk) 19:40, 16 July 2016 (UTC)
thread_title:  Sources 

message: Actually, the name collision not that coincidental: both are the same Latin prefix com-.
Joe Forster/STA (talk) 19:09, 18 December 2017 (UTC)
thread_title:  .com (command) = .com (commercial)