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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)
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.
By the way, MS-DOS and CP/M "compatibility" is only somewhat possible if you confine yourself to the system functions of MS-DOS version 1; a whole new series of radically revamped DOS function calls was introduced with DOS 2.0 in 1983 (adding file handles, subdirectory support, and ASCIIZ strings, among other things), and very quickly came to be used in preference to the roughly equivalent DOS 1 functions for most purposes by most programs. By 1985, CP/M compatibility was only of interest to a quite small number of PC users... AnonMoos ( talk) 09:51, 26 October 2008 (UTC)
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)
I think the word "capitalise" is being misused. Capitalism suggests exploitation for the purpose of generating revenue, whereas virus writers operate for other reasons. So I'm changing it to "take advantage". Bbi5291 ( talk) 19:41, 24 June 2008 (UTC)
Take advantage is clearer so I left it be. The use of capitalise was correct. See dictionary.com definition 7. TLConrow ( talk) 02:47, 21 September 2008 (UTC)
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)
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)
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)
I read somewhere, though I forget where, that the ".COM stands for Command File" was simply a common misconception and that COM is actually "Common Image". This is not simply a piece of idle gossip as I believe I read it in a respected textbook, however I cannot seem to find which one. Anyone able to enlighten me upon the truth and perhaps update the article accordingly? -- 213.105.186.124 ( talk) 01:30, 10 July 2012 (UTC)
I have never seen .com used as a virus. LMGN ( talk) 17:29, 13 December 2015 (GMT)
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)
Actually, the name collision not that coincidental: both are the same Latin prefix com-.
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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)
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.
By the way, MS-DOS and CP/M "compatibility" is only somewhat possible if you confine yourself to the system functions of MS-DOS version 1; a whole new series of radically revamped DOS function calls was introduced with DOS 2.0 in 1983 (adding file handles, subdirectory support, and ASCIIZ strings, among other things), and very quickly came to be used in preference to the roughly equivalent DOS 1 functions for most purposes by most programs. By 1985, CP/M compatibility was only of interest to a quite small number of PC users... AnonMoos ( talk) 09:51, 26 October 2008 (UTC)
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)
I think the word "capitalise" is being misused. Capitalism suggests exploitation for the purpose of generating revenue, whereas virus writers operate for other reasons. So I'm changing it to "take advantage". Bbi5291 ( talk) 19:41, 24 June 2008 (UTC)
Take advantage is clearer so I left it be. The use of capitalise was correct. See dictionary.com definition 7. TLConrow ( talk) 02:47, 21 September 2008 (UTC)
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)
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)
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)
I read somewhere, though I forget where, that the ".COM stands for Command File" was simply a common misconception and that COM is actually "Common Image". This is not simply a piece of idle gossip as I believe I read it in a respected textbook, however I cannot seem to find which one. Anyone able to enlighten me upon the truth and perhaps update the article accordingly? -- 213.105.186.124 ( talk) 01:30, 10 July 2012 (UTC)
I have never seen .com used as a virus. LMGN ( talk) 17:29, 13 December 2015 (GMT)
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)
Actually, the name collision not that coincidental: both are the same Latin prefix com-.