The 12 KB that Windows just can't seem to quit

Icons from a more civilized time

Windows deposits a huge number of files onto a user's PC, some of which are essential for the operating system, and others that are a reminder of gentler times. Microsoft veteran Raymond Chen this week took another trip down memory lane to the pixel-tastic world of moricons.dll on his Old New Thing blog.

As the file's name suggests, moricons.dll contains more icons. However, its size, a mere 12,288 bytes, hints at more compact icons than today's AI-generated monstrosities. These icons date back decades to the halcyon days of Windows 3.1.

In the era of Windows 3.0, some old MS-DOS programs could be run in a window. An application existed that could scan a user's hard drive for well-known executables and create a Program Information File (PIF) containing the MS-DOS configuration and an icon for the executable if a user wanted. The application would then be added to the Non-Windows Applications group in Program Manager.

The icon was a plain gray image labeled "DOS."

In Windows 3.1, Microsoft mixed things up a bit. Rather than create a PIF and add a plain icon, the Set Up Applications program could pick a more attractive icon. "When you clicked it," said Chen, "it still ran as an MS-DOS program, but at least the icon was prettier."

"Initially, these icons were placed in progman.exe, but as the number of icons grew, it became clear that they needed their own home instead of squatting inside the Program Manager binary. So the icons started getting added to a DLL called MORICONS.DLL because, well, they were more icons."

We took a look at the moricons.dll file that comes with Windows 11, and it is a nostalgic glimpse at another era. Turbo Pascal and Quattro Pro are there, as are a range of WordPerfect images. Lotus 123 and cc:Mail are present, and even dear old Sidekick 2 is in the collection.

"This moricons.dll icon library has carried forward ever since. Windows itself created those Program Manager icons, and those Program Manager icons turned into shortcut files in Windows 95, and those shortcut files would then migrate forward as you upgraded Windows.

"In theory, the compatibility chain could have been abandoned with the introduction of 64-bit Windows since there was no upgrade path from 32-bit Windows to 64-bit Windows (clean installs only), and because 64-bit Windows didn't support MS-DOS programs any more, so you couldn't reinstall them onto your 64-bit Windows system."

The DLL survived the 64-bit port. Chen recalled that most of the port was mechanical, rather than focusing on old 32-bit components which could be deleted.

Plus, the DLL was only 12 KB, and maybe, just maybe, somebody somewhere was using those icons for something.

"Better to let sleeping dogs lie and eat the 12 kilobytes." ®