Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!sdd.hp.com!wuarchive!emory!gatech!mcnc!uvaarpa!haven!decuac!shlump.nac.dec.com!sousa.enet.dec.com!pinbot.enet.dec.com!ervin
From: ervin@pinbot.enet.dec.com (Joseph James Ervin)
Newsgroups: comp.sys.handhelds
Subject: (HP48SX)  Strange behavior...bug?
Message-ID: <990@sousa.enet.dec.com>
Date: 22 Mar 91 13:48:53 GMT
Sender: newsa@sousa.enet.dec.com
Reply-To: ervin@pinbot.enet.dec.com (Joseph James Ervin)
Organization: Digital Equipment Corporation
Lines: 46

I have recently been experimenting with the KEY function on my HP48SX in
preparation for some games programming, and I have seen some strange
behavior that points to a possible bug.  I wanted to post my
observations here so that other people could try to reproduce the
behavior.

What I'm seeing is an inconsistency when using the KEY function.  The
KEY function returns a 0 to level 1 if no key is pressed, and if a key
is pressed returns a 1 in level 1 and the keycode in level 2.

Following the style of the example use in the programmers reference
manual, I wrote the following program.

\<< DO UNTIL KEY END \>>

This simple program stays in the indefinite loop until a key is pressed,
and leaves the keycode on the stack when it leaves the loop.  This seems
to work fine, which is to be expected since this is taken directly from
the reference manual.  

Next, I tried this simple variation;  I wanted to wait for 10 key
presses and then exit.

\<< 1 10 FOR I DO UNTIL KEY END NEXT \>>

This program should wait for 10 key presses, and leave the 10 keycodes
on the stack.  Unfortunately, the actual number of key presses I must
make tends to vary from 10 to as high as 14.  I realize that the KEY
function does not wait for a key press, but I see the same behavior even
when I press the keys very slowly (once a second) an very deliberately
(firmly holding the key down each time I press one).

I am very surprised that this simple program would behave so unpredictably.  

The other annoying thing  about this program is that sometimes it works
fine, being able to "see" all 10 of my key presses even if I do them
rather fast.  At other times the program seems to miss many of them,
requiring me to press 13 or 14 keys to get the program to exit.  I
almost wonder if it might be temperature dependent.

Could people out there please try the above program and post a response
to this message indicating the success or failure of the program?

Thanks,

>>>Joe Ervin