Comment by nineties

Sorry. I found a bug in the *Hello World* program I posted above. The Q operation requires an integer argument, an exit status.

So

    kHtketkltkltkotk tkWtkotkrtkltkdtk!tk:k0-tQ

is wrong. The below is correct.

    kHtketkltkltkotk tkWtkotkrtkltkdtk!tk:k0-tk0k0-Q