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Hi all,
i need a little help, i have an HP50G.
in the menu APPS -> I/0 functions its possible to change the communication way between 3 choices :
i need to do it by program, if possible in RPL
or to have an utility that take as entry my choice and do the job.
can someone help me ?
i have ever look in the FLAGS



have you compared flags contents (RCLF) before and after setting one of the two port comm modes? IIRC one of the flags controls it but is not listed in the Flags Mode, Choose list...

I am not with an HP50G in hands right now, sorry...

Luiz (Brazil)

Edited: 30 Dec 2009, 6:52 a.m.

System flag 78.


thank's for your precious help


Sorry for my naïve remark, I have never touch a HP50g.

How can a single (binary) flag be the director of a three-state positon (USB - IRDa - SERIAL) ?
Is this flag more than binary (set or down) or is there samewhere another trick I am missing ?

Thank to elucidate this and bring me the light of understanding.


flag 78 controls only cable selection (USB or Serial).


Luiz (Brazil)

Edited: 31 Dec 2009, 6:48 a.m.

I am not familiar with how the 50g works, but perhaps the flag is not binary. Perhaps it can be 1, 2, or 3.


all flags in the HP50G (all-purpose, user flags or system flags) are binary: cleared (0) or set (1). They can be tested with one of two possible answers: true (1) or false (0). One single bit only.


Luiz (Brazil)

Sorry about that.

The only problem with setting it problematically is that flag 78 doesn't show up in the flag list. Flag 33 sets either IR or wire, and then if 33 is clear so wire is active, 78 set means serial instead of USB.