Aversion to History: A Pkzip/Wikipedia Story

A couple of years ago, while sifting through lots of ZIP archives from old Shareware CD-ROMs, I found quite a few that couldn’t be unzipped, either because they were corrupted, encrypted, or used compression methods that were no longer supported by modern ZIP utilities. That took me on a journey of ZIP (and ARC) decompression, and I created some new PCjs decompression tools in the process, including the ability to create disk images directly from ZIP files.

Of course, you can’t go down that rabbit hole without digging into the history of the ZIP file format, or the person who developed it, Phil Katz, or the first program to create ZIP files: PKZIP. There’s a lot of history there, and many other rabbit holes you can go down, but this post is going to focus on one “hole” in particular.

PKZIP Version History

Specifically, I’m talking about the PKZIP Wikipedia Page and the history of its version history.

I remembered visiting that Wikipedia page several years ago and seeing a fairly detailed history of PKZIP and all its versions. But when I visited the page earlier this year, the version history was gone.

At first, I thought perhaps I misremembered where I’d seen that version history, so I searched the web, and one of the top results was “Survey of PKZIP versions for MS-DOS”” from Jason Summer’s Entropymine blog, which, coincidentally, mentioned the same Wikipedia page:

“I wanted to know exactly what versions of the old PKZIP compression software were publicly released for MS-DOS, and some basic characteristics about them, particularly what compression methods they used when compressing files. Sure, Wikipedia has a list, but it wasn’t quite what I wanted, and it omitted at least one version I was pretty sure existed.”

So I wasn’t wrong. In 2019, Wikipedia had a list, and I was pretty sure I’d seen the same list back in 2022. But now it was gone.

It’s not hard to find the old list – once you know it existed – by browsing the page’s history and choosing, for example, t…