Paul, Bill, Regarding APL-11 and its source code. This was the focus of a software archeology effort in 2021. I had bought the APL-11 package from DECUS on 9-track tape when DEC donated it to DECUS when they decided to no longer sell it. Then could be ordered from the DECUS Library (Order No. 11-SP-25). Then on the RSX SIG tape RSX85A:[370,360], Bob Awde from General Mills provided a few modified .MAC, .ODL, and .CMD files that converted APL-11 to a I/D space task with FCS Supervisor mode. This gives you a workspace of just over 52,000 bytes on RSX11M+ with a I/D space CPU. Unfortunately, there were changes made to how TKB overlays task images and these patches and in fact the original source e code could no longer be compiled with RSX TKB. The task images from the original DECUS source ran but one could not rebuild the task from the Macro-11 sources. I struggled with this for a number of years until I got a couple (much smarter than I) friends to get interested in fixing. It. First, Lee Gleason, figured out what was happening with TKB and the overlays and managed to make some hacks that created a I/D space version of APL-11. He described that work on his RSX blog: https://rsx11.blogspot.com/2021/02/ Then Johnny Billquist saw the blog and decided to work on the distribution. He fixed the .ODL and .CMD to work properly with the new TKB overlay mechanisms, and while he was at it, fixed several bugs in the original APL-11 that affected a number of things. He also modified it to fix a Y2K problem and to handle named directories. Today if you use Johnny’s RPM package manager APL-11 can be downloaded and the latest version is V2.2.2 Also, there is a VT220 downloadable APL font on that RSX85A Sig tape in [370,361] and a task to compose new fonts. I also had an APL-11 user’s manual that I scanned and made available at: http://www.rsx11m.com/APL-11-Ref-Man.pdf The release notes are at http://www.rsx11m.com/APL11ins.pdf The APL-11 quick reference card is at http://www.rsx11m.com/APL_Reference_Card.pdf You can also get the APL-11 manuals from Johnny’s virtual PDP-11/74 MIM at http://mim.softjar.se/manuals/LAYERED/ The latest version of the modified sources could be obtained from Johnny as well. The quick reference card is especially helpful to learn the two letter replacements for APL characters. For example, the square “quad” is .QD so to see the available workspace .QDWA works with standard ascii terminals. Matrix divide (Quad, back-space Divide symbol) is .DQ so .DQM inverts matrix M. Best, Mark Matlock