Bill, I?ve looked extensively to see if I can find the original distribution tape image and can?t find it. At one point DEC donated the APL-11 to DECUS and I think that is when I got it back in 1984 or so. The files I have include the Macro-11 source code which as near as I can tell was not on the DEC distribution when it was a layered product. I now think that the copy of APL-11 I have must have come from a restored backup tape from my old system. In the DEC distribution, it was a DOS-11 tape which could be read by all the PDP-11 OSes as you say. I just attempted to create a DOS-11 tape similar to the DEC distribution, but when I try to run the installation against it I get a task build of APL that doesn?t work. It immediately exits and I think is due to some differences between the auto overlay code in RSX11M+ V4.6 and the V2.1 M+ that I used to have. I added the .MAC files and .CMD files (for assembly, and linking) to the tape and make it available at: http://www.rsx11m.com/apl11.tap <http://www.rsx11m.com/apl11.tap> Let me know if that works for you. It may build under RSTS fine. A backup plan to make it available is that also on the same web site are two disk images for the PiDP-11/70 folks that is a complete RSX11M+ V4.6 ready to run under Simh. On the DU1 disk image in [201,50] and [201,200] are all the APL-11 files I have. That system also installs a working APL-11 for RSX. Mark