is an interesting operating system
Found at: whitemesa.net:70/tops20
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