For some reason, probably the pandemic, recent posts regarding the verb fork_jtask_ evoked old memories. In the late '70s, while reading a passage in a book describing Von Newman's scheme for constructing self-replicating machines, I realized I could design a self-replicating process capable of running in the computer environment at work. The computer was a Burroughs B6700 and it had enabled the Inter Process Communication (IPC) facility which allowed a process to run another process. I wrote a tiny program and showed it as a curiosity to a few of my colleagues telling them that it would likely overwhelm the computer; but, for the same reason, I could not test it.
Shortly after I went to work for another institution and, in the early '80s, I moved from Mexico to England and I bought a little microcomputer called Sinclair QL. It had a multitasking OS called QDOS and a BASIC variant called SuperBASIC which was also the QDOS' command-line interpreter. So, I rewrote and ran a version of my tiny program and, as expected, the only way out was to, literally, pull-the-plug. (Incidentally, the machine which looked almost like a keyboard was also capable to run QL APL, which was a special version of MicroAPL's APL.68000.) I had swamped not only j but also the OS a few times before, but never intentionally. So, this is a first for me, the following fleeting script (beware of line-wrapping) runs in an earlier custom version of the j interpreter on Windows 10 but it should be able to run in the latest and greatest public versions of j and also on other platforms (changing what needs to be changed); however, my strong advice, unless one likes to live dangerously, is: DO NOT RUN IT! NB. Saved as J:/temp/Virus.ijs (2!:55)@:_:@:(([fork_jtask_)^:2) '"J:/Program Files/J/bin/jqt.exe" "J:/temp/Virus.ijs"' PS. Many years later while visiting an old friend in New York, who used to be a member of the staff operating the B6700, he told me that one of the most stressful times ever at work was when the B6700 suddenly kept crashing and crashing for a few days, even missing a payroll deadline. The staff and the Burroughs technicians could not find anything wrong with the hardware. The issue was that the system was too clever, after a crash it would automatically restart all the processes which were interrupted. Immediately after identifying the culprit, the sneaky tiny program which was very familiar to me, the general access to the IPC facility was disabled... Long live the verb fork_jtask_! :) ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
