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From: herman@corpane.uucp (Harry Herman)
Newsgroups: comp.sys.handhelds
Subject: Re: (HP48SX) Strange behavior...bug?
Message-ID: <1991Mar24.191810.7196@corpane.uucp>
Date: 24 Mar 91 19:18:10 GMT
References: <990@sousa.enet.dec.com> <14295@life.ai.mit.edu>
Organization: Corpane Industries Inc.
Lines: 36

In <14295@life.ai.mit.edu> bson@rice-chex.ai.mit.edu (Jan Brittenson) writes:

>In a posting of [22 Mar 91 13:48:53 GMT]
>   ervin@pinbot.enet.dec.com (Joseph James Ervin) writes:

> > 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 \>>
> >
> > Unfortunately, the actual number of key presses I must
> > make tends to vary from 10 to as high as 14.
>   The same happens on my Rev D. It is further illustrated by pressing
>the shift keys. The shift key annunciators should only flicker, but
>sometimes stay on, indicating that the stroke was caught by something
>other than KEY. I bet this is why Tetris sometimes misses key strokes.

>						-- Jan Brittenson
>						   bson@ai.mit.edu

I have noticed that both my Rev. B and Rev. D calculators seem to miss
keypresses occasionally when used for normal (non-program) uses.  I find
myself having to watch the display and see if it has what I have typed.
Usually this come when pressing several keys fast, but I have also seen
it happen when pressing keys slower trying to get around the missing key
problem.  Perhaps the problem is in the keyboard interrupt, or in an
interaction between the keyboard interrupt and another interrupt, like
the clock interrupt.  I know that a hardware system that I program for
has LOUSY serial I/O response when the parallel I/O card (for encoder
interrupts) is run at the same interrupt priority level as the serial
I/O card (for terminal I/O).


				Harry Herman
				herman@corpane	or
				...uunet!ukma!corpane!herman