ITS 138 from ~1967 found

Two years ago, I was searching for ITS information online, when I found a passage in a 1980s book called “The Tomorrow Makers”. The author interviewed Sussman in his office, and he showed a 1967 listing of ITS 138 to the author. I contacted Sussman and he confirmed he still had it. Since I’m nowhere near Massachusetts I have been agonizing over how to get it scanned. Now I’m getting some help from MIT Museum staff. 25 pages have been processed so far, with around 100 more coming in later.

Unfortunately this is only ITS itself, i.e. the monitor, or kernel. There would have to be a dozen or so tools for a full system.


The entire 133-page listing has now been typed in twice over by a group of volunteers. The original source file has been reconstructed with a high degree of confidence, and it assembles cleanly with an old version of MIDAS.

This wiki page summarizes some information about the listing and its contents:


Here it is, running on PDP-6 emulator. We don’t have a proper DDT for it yet; this is an archaic - but working - version found on an old DECtape.


Funny looking zeroes on that terminal.

That is a OCTAL zero. :slight_smile:
I like the idea of the , separating every 4 octal digits. 12,24,36 bits

I got the font from a patent:


Thanks! I’ve started to search for the font and checked some PDF manuals, but I think I haven’t found it or cancelled as most PDFs are too large.