Commenter Koro asks why you can rename a COM file to EXE without any apparent ill effects. (James MAstros asked a similar question, though there are additional issues in James’ question which I will take up at a later date.)

Initially, the only programs that existed were COM files. The format of a COM file is… um, none. There is no format. A COM file is just a memory image. This “format” was inherited from CP/M. To load a COM file, the program loader merely sucked the file into memory unchanged and then jumped to the first byte. No fixups, no checksum, nothing. Just load and go.

The COM file format had many problems, among which was that programs could not be bigger than about 64KB. To address these limitations, the EXE file format was introduced. The header of an EXE file begins with the magic letters “MZ” and continues with other information that the program loader uses to load the program into memory and prepare it for execution.

And there things lay, with COM files being “raw memory images” and EXE files being “structured”, and the distinction was rigidly maintained. If you renamed an EXE file to COM, the operating system would try to execute the header as if it were machine code (which didn’t get you very far), and conversely if you renamed a COM file to EXE, the program loader would reject it because the magic MZ header was missing.

So when did the program loader change to ignore the extension entirely and just use the presence or absence of an MZ header to determine what type of program it is? Compatibility, of course.

Over time, programs like FORMAT.COM, EDIT.COM, and even COMMAND.COM grew larger than about 64KB. Under the original rules, that meant that the extension had to be changed to EXE, but doing so introduced a compatibility problem. After all, since the files had been COM files up until then, programs or batch files that wanted to, say, spawn a command interpreter, would try to execute COMMAND.COM. If the command interpreter were renamed to COMMAND.EXE, these programs which hard-coded the program name would stop working since there was no COMMAND.COM any more.

Making the program loader more flexible meant that these “well-known programs” could retain their COM extension while no longer being constrained by the “It all must fit into 64KB” limitation of COM files.

But wait, what if a COM program just happened to begin with the letters MZ? Fortunately, that never happened, because the machine code for “MZ” disassembles as follows:

0100 4D            DEC     BP
0101 5A            POP     DX

The first instruction decrements a register whose initial value is undefined, and the second instruction underflows the stack. No sane program would begin with two undefined operations.

Full Article – http://blogs.msdn.com/oldnewthing/archive/2008/03/24/8332730.aspx

Commenter Koro asks why you can rename a COM file to EXE without any apparent ill effects. (James MAstros asked a similar question, though there are additional issues in James’ question which I will take up at a later date.)

Initially, the only programs that existed were COM files. The format of a COM file is… um, none. There is no format. A COM file is just a memory image. This “format” was inherited from CP/M. To load a COM file, the program loader merely sucked the file into memory unchanged and then jumped to the first byte. No fixups, no checksum, nothing. Just load and go.

The COM file format had many problems, among which was that programs could not be bigger than about 64KB. To address these limitations, the EXE file format was introduced. The header of an EXE file begins with the magic letters “MZ” and continues with other information that the program loader uses to load the program into memory and prepare it for execution.

And there things lay, with COM files being “raw memory images” and EXE files being “structured”, and the distinction was rigidly maintained. If you renamed an EXE file to COM, the operating system would try to execute the header as if it were machine code (which didn’t get you very far), and conversely if you renamed a COM file to EXE, the program loader would reject it because the magic MZ header was missing.

So when did the program loader change to ignore the extension entirely and just use the presence or absence of an MZ header to determine what type of program it is? Compatibility, of course.

Over time, programs like FORMAT.COM, EDIT.COM, and even COMMAND.COM grew larger than about 64KB. Under the original rules, that meant that the extension had to be changed to EXE, but doing so introduced a compatibility problem. After all, since the files had been COM files up until then, programs or batch files that wanted to, say, spawn a command interpreter, would try to execute COMMAND.COM. If the command interpreter were renamed to COMMAND.EXE, these programs which hard-coded the program name would stop working since there was no COMMAND.COM any more.

Making the program loader more flexible meant that these “well-known programs” could retain their COM extension while no longer being constrained by the “It all must fit into 64KB” limitation of COM files.

But wait, what if a COM program just happened to begin with the letters MZ? Fortunately, that never happened, because the machine code for “MZ” disassembles as follows:

0100 4D            DEC     BP
0101 5A            POP     DX

The first instruction decrements a register whose initial value is undefined, and the second instruction underflows the stack. No sane program would begin with two undefined operations.

Full Article – http://blogs.msdn.com/oldnewthing/archive/2008/03/24/8332730.aspx

Windows administrators are smack-dab in the middle of a challenging security balancing act: how to enable easy access to resources while still meeting ever-increasing information and network security requirements. As this feature describes, a great way to help strike the appropriate balance between access and security is to shift from traditional connectivity models to one that seeks to define network access in a more logical and policy-centric fashion.

Full Article – http://blogs.technet.com/tnmag/archive/2008/03/25/policy-driven-network-access-with-windows-server-2008.aspx

This guide provides a comprehensive product comparison of the Visual Studio 2008 IDE products. It does not provide data about Visual Studio Team System 2008 Team Foundation Server, Visual Studio Team System 2008 Team Explorer, or Visual Studio Team System 2008 Test Load Agent. This guide is provided for illustrative purposes only.

link – http://www.microsoft.com/downloads/details.aspx?FamilyID=727bcfb0-b575-47ab-9fd8-4ee067bb3a37&DisplayLang=en

Mozilla has confirmed that Firefox 3 will launch in June, although the organisation is urging users to switch to the new browser already.

Until now, Mozilla has discouraged average internet users from moving on from Firefox 2, which was launched in October 2006. But Mozilla Corp vice president of engineering, Mike Schroepfer, says the beta four version of the software is ready for the general public. “In many ways it (Firefox 3) is much more stable than anything else out there,” he claims.

Full Article – http://www.pcpro.co.uk/news/180777/firefox-3-will-launch-in-june.html

Mozilla has confirmed that Firefox 3 will launch in June, although the organisation is urging users to switch to the new browser already.

Until now, Mozilla has discouraged average internet users from moving on from Firefox 2, which was launched in October 2006. But Mozilla Corp vice president of engineering, Mike Schroepfer, says the beta four version of the software is ready for the general public. “In many ways it (Firefox 3) is much more stable than anything else out there,” he claims.

Full Article – http://www.pcpro.co.uk/news/180777/firefox-3-will-launch-in-june.html

It’s time to say goodbye to an old friend. Windows XP Service Pack 3 (SP3), due in the second quarter of 2008, will be the final XP service pack , according to Microsoft. It can’t come a moment too soon: XP SP2 (see my review) shipped over three years ago at this writing, and the company has since shipped hundreds of hot-fixes for the OS, giving users a painful updating experience, with multiple reboots. XP SP3 will consolidate all of these fixes into a single package and, surprisingly, add a few new features, including some that–go figure–debuted first in XP’s successor, Windows Vista. Here’s what I know about Windows XP Service Pack 3.

Full Article – http://www.winsupersite.com/faq/xp_sp3.asp

Microsoft is experimenting with a potential product that would give companies more control over the electronic messages their staff exchange in order to better meet regulatory requirements and e-discovery laws.

Employee Managed Mailbox (EMM), is being used internally at Microsoft and may eventually turn into a commercial offering, according to Joel Freedman, chief financial officer at Microsoft Canada.

“Instead of e-mail that would be utilizing the hard drive, you’d have e-mail that gets managed by a server,” he said, adding that a server-based product could help companies do a better job of adhering to compliance-related policies. “You could have a one-month, one-year, or three-year limit on retention [of an e-mail message], for example.”

Freedman suggested EMM could become a direct way for Microsoft to assist corporations who are struggling to keep up with accounting, privacy, and other rules that increasingly govern the way they handle information.

Although some vendors are developing specific tools to match the requirement of the U.S. Sarbanes-Oxley legislation or Canada’s Bill 198, many firms, Microsoft included, are making the best of existing office productivity tools to keep themselves out of trouble.

“For most companies, it’s Office and e-mail,” said Jeff Dunmall, principal with Toronto-based IT consulting firm iMason, which specializes in Microsoft-based technologies. “The problem is if you send out something about a new process via e-mail to five people for comment or approval, you’ve suddenly got five different versions of that document.”

Full Article – http://www.infoworld.com/article/08/03/20/Microsoft-experiments-with-managed-e-mail_1.html?source=rss&url=http://www.infoworld.com/article/08/03/20/Microsoft-experiments-with-managed-e-mail_1.html

The people who are drafting the new user interface guidelines for Windows 7 plan to build the Ribbon, Jewel and “other new UI concepts” natively into the Windows platform.

Ultimately, they want software developers to avoid the prehistoric Win32 UI framework from no other than Windows 95. Instead, use this new lightweight and high performance markup-based UI framework to build “rich, graphics and animated user interfaces”. The Ribbon and Jewel (button in the top left corner) will be a part of this new framework. It sounds very much like WPF, except native.

Full Article – http://www.istartedsomething.com/20080322/ribbon-in-windows-7-application-near-you/

Microsoft has begun inviting selected testers to be part of a beta of a new, consumer-focused Office-family product, codenamed “Albany.”

The beta invitation for Albany is cryptic, according to testers who received the invite and asked not to be named. Albany will be aimed at home PC users, not business customers, and will include both a software and a services component. The individuals who’ve been invited into the private, limited beta so far are those who’ve previously beta-tested Office releases.

Update: I hear some folks who helped Microsoft test Windows Live OneCare all-in-one consumer security/backup service also got invites to the Albany beta.

Full Article – http://blogs.zdnet.com/microsoft/?p=1287

Microsoft has begun inviting selected testers to be part of a beta of a new, consumer-focused Office-family product, codenamed “Albany.”

The beta invitation for Albany is cryptic, according to testers who received the invite and asked not to be named. Albany will be aimed at home PC users, not business customers, and will include both a software and a services component. The individuals who’ve been invited into the private, limited beta so far are those who’ve previously beta-tested Office releases.

Update: I hear some folks who helped Microsoft test Windows Live OneCare all-in-one consumer security/backup service also got invites to the Albany beta.

Full Article – http://blogs.zdnet.com/microsoft/?p=1287

Today Microsoft delivered the Hyper-V release candidate (RC) code broadly to customers and partners. This is a key milestone signaling that Microsoft is on track to deliver Windows Server 2008 Hyper-V virtualization by August 2008. Hyper-V RC is a feature-complete version and has three main enhancements from the beta release:

• An expanded list of tested and qualified guest operating systems including: Windows Server 2003 SP2, Novell SUSE Linux Enterprise Server 10 SP1, Windows Vista SP1, and Windows XP SP3.

Full Article – http://bink.nu/news/hyper-v-rc-released.aspx

Windows Vista Service Pack 1 has been released in a staggered fashion to a variety of channels, and Windows XP Service Pack 3 is right around the corner. So why should you care if you’re also considering adopting Windows Server 2008? How do the respective service packs fit into the overall design?

Let’s take a look at each of them.

Windows Vista Service Pack 1

Perhaps the most well-known change in store for Vista Service Pack 1 users is the alleged improvement in file-copying speeds between SP1 machines and Windows Server 2008 computers. Some tests — using pre-release builds of both of these products — showed a comparatively significant improvement in transferring both a large number of smaller files and a single, extremely large file over a link to a Windows Server 2008 machine.

Full Article – http://www.computerworld.com/action/article.do?command=viewArticleBasic&articleId=9069358&source=rss_topic125

These guides will assist IT Professionals in evaluating and deploying Windows Vista SP1 and are downloadable versions of the SP1 guides found in the Windows Vista Technical Library. (http://technet2.microsoft.com/WindowsVista/en/library/90a564b9-34af-4a6b-937f-324e1862244b1033.mspx)

Download Link – http://www.microsoft.com/downloads/details.aspx?FamilyID=e71f0083-1013-4f9c-a3f9-c56e7120a5e9&DisplayLang=en

These release notes provide important information you should know before deploying and using Windows Vista SP1. You should familiarize yourself with all of the known issues in this document prior to installing the software.

For an overview of significant changes and improvements in SP1, see http://go.microsoft.com/fwlink/?LinkId=107921
For a list of the hotfixes and security updates included in SP1, see http://go.microsoft.com/fwlink/?LinkId=107922