user31881: In connection with another project, I am looking on the internet for some free versions of older chess engines, such as some of the old Chessmaster engines from the 1990s.  I would even take an old Fritz engine if there were one.
I'm wanting to compare older chess engine output to modern chess engine output. I'm aware that engines like Stockfish are far superior in playing strength than anything made in the 1990s.

user31898: The Internet Archive has lots of browser-playable Chess games:
https://archive.org/details/softwarelibrary_msdos_games?query=chess&sort=-downloads

user7147: Ed Schröder has made a pretty sizable collection of old chess software (including the code from some old dedicated chess computers, turned into UCI engines) on his web site for free download.  Look in the sections labelled "OLD", "REBEL13", and "DEDICATED -> DEDICATED AS UCI".

user16027: The other excellent answer by Brian Towers ♦ provides individual perhaps-ideal direct links, but you may see further benefit from your own search on The Internet Archive (https://archive.org) which has a vast collection of ancient (ha) software, including some chess software
A query like this may be all you need to get at them
https://archive.org/details/software?query=chess&and[]=subject%3A%22chess%22
The oldest engine I could find via that query is MyChess, and you can just step by-years with a filter at the left

MYCHESS is one of the oldest chess games ever made. It was developed by David Kittinger (the man behind the famous Chessmaster games) in 1979, although the DOS version was published in 1984.

https://archive.org/details/mychess

user4418: Fritz 5.32 (I'm guessing the first 32 bit version) dates from about 20 years ago, I think. That is available for download via the wayback machine here. Note that you will probably need to install it in compatibility mode as Windows 98/ME on Windows 7. Not sure if you can do this on Win 10.
The oldest version of Crafty I could find, another old favourite, was 8.11 download here.
Chessmaster 8000, another Windows 98/ME program is available for download on this website.
Finally, if you can run a DOS box emulator then all the way back from 1990 is version 3.1 of GNUChess from this website. 181 kb (!) zip file here.

31881: <p>In connection with another project, I am looking on the internet for some free versions of older chess engines, such as some of the old Chessmaster engines from the 1990s.  I would even take an old Fritz engine if there were one.</p>
<p>I'm wanting to compare older chess engine output to modern chess engine output. I'm aware that engines like Stockfish are far superior in playing strength than anything made in the 1990s.</p>
 31898: <p>The Internet Archive has lots of browser-playable Chess games:</p>
<p><a href="https://archive.org/details/softwarelibrary_msdos_games?query=chess&amp;sort=-downloads" rel="nofollow noreferrer">https://archive.org/details/softwarelibrary_msdos_games?query=chess&amp;sort=-downloads</a></p>
 7147: <p><a href="https://www.chessprogramming.org/Ed_Schroder" rel="nofollow noreferrer">Ed Schröder</a> has made a pretty sizable collection of old chess software (including the code from some old dedicated chess computers, turned into UCI engines) on his <a href="https://rebel13.nl/" rel="nofollow noreferrer">web site</a> for free download.  Look in the sections labelled &quot;OLD&quot;, &quot;REBEL13&quot;, and &quot;DEDICATED -&gt; DEDICATED AS UCI&quot;.</p>
 16027: <p>The other <a href="https://chess.stackexchange.com/a/39017/16027">excellent answer by Brian Towers ♦</a> provides individual perhaps-ideal direct links, but you may see further benefit from your own search on The Internet Archive (<a href="https://archive.org" rel="nofollow noreferrer">https://archive.org</a>) which has a vast collection of ancient (ha) software, including some chess software</p>
<p>A query like this may be all you need to get at them<br />
<a href="https://archive.org/details/software?query=chess&amp;and%5B%5D=subject%3A%22chess%22" rel="nofollow noreferrer">https://archive.org/details/software?query=chess&amp;and[]=subject%3A%22chess%22</a></p>
<p>The oldest engine I could find via that query is MyChess, and you can just step by-years with a filter at the left</p>
<blockquote>
<p>MYCHESS is one of the oldest chess games ever made. It was developed by David Kittinger (the man behind the famous Chessmaster games) in 1979, although the DOS version was published in 1984.</p>
</blockquote>
<p><a href="https://archive.org/details/mychess" rel="nofollow noreferrer">https://archive.org/details/mychess</a></p>
 4418: <p>Fritz 5.32 (I'm guessing the first 32 bit version) dates from about 20 years ago, I think. That is available for download via the wayback machine <a href="https://web.archive.org/web/20170827180745/http://www.top-5000.nl/dl/fritz532.zip" rel="noreferrer">here</a>. Note that you will probably need to install it in compatibility mode as Windows 98/ME on Windows 7. Not sure if you can do this on Win 10.</p>
<p>The oldest version of Crafty I could find, another old favourite, was 8.11 download <a href="https://craftychess.com/downloads/source/crafty-8.11.zip" rel="noreferrer">here</a>.</p>
<p>Chessmaster 8000, another Windows 98/ME program is available for download on <a href="https://www.myabandonware.com/game/chessmaster-8000-doa" rel="noreferrer">this website</a>.</p>
<p>Finally, if you can run a DOS box emulator then all the way back from 1990 is version 3.1 of GNUChess from this <a href="https://archive.org/details/gnuchess_201910" rel="noreferrer">website</a>. 181 kb (!) zip file <a href="https://archive.org/download/gnuchess_201910/gnuchess.zip" rel="noreferrer">here</a>.</p>
