(Free42) tips & tricks: local flags

[rprosperi]

(07-24-2020 03:34 PM)Thomas Okken Wrote:  It looks like the real HP-42S does not have this mode. I checked with Emu42 and the HP82240B Printer Simulator.

It sounds like implementing this in Free42 would require changing most or all occurrences of

Code:

if flag 15 set and flag 55 set
    PRX

to

Code:

if flag 15 set and flag 55 set
    if flag 16 set
        PRSTK
    else
        PRX

Is that what the real 41C with IL printer does? I have a 41CX but no printer so I can't check that either, and i41CX on my phone only emulates the 82143A where the printing mode is controlled by a hardware switch and flags 15 & 16 have no effect...

It would make sense for it to print the stack when STO ST operations are performed. Does the real thing do that?

That logic makes sense, except you should probably be using flag-21 instead of flag-55. Flag-55 is intended to indicate the physical presence of a printer (or module if IR). At each power-on the h/w sets SYSTEM flag-55 if it detects such presence and then it sets USER flag-21 to match the state of flag-55; thereafter the user can enable printer access by leaving flag-21 set, or disable printer access by clearing flag-21.