is an interesting operating system

Found at: whitemesa.net:70/tops20

                     TOPS-20 ARCHIVE
 TOPS-20 is an interesting operating system from an earlier
 age. However it's not too late to enjoy it - if you run
 the Panda TOPS-20 system on a Linux PC using the KLH20
 emulator. Download and extract the distribution and follow
 the instructions therein. Everything you need is contained
 in the distribution, even source code for the emulator.
 The Panda distribution is no longer being maintained but
 questions can be posted to the alt.sys.pdp10 news group
 where some Panda TOPS-20 users may be found.

Panda Tops-20 Distribution Web Page

TOPS-20 Documention