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HP Forum Archive 20

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15C-LE Blinking
Message #1 Posted by dbatiz on 23 Oct 2011, 11:50 p.m.

Is it normal for an overflow condition to make the display blink on a 15C? On my 15C-LE, if I type 70!, i get 9.999999 99 blinking. I can then keep doing other problems, but the display keeps blinking until I use the "back arrow" key. Is this normal?

Very Respectfully,

David

      
Re: 15C-LE Blinking
Message #2 Posted by Michael de Estrada on 23 Oct 2011, 11:56 p.m.,
in response to message #1 by dbatiz

Yes. It is normal.

      
Re: 15C-LE Blinking
Message #3 Posted by MK-52 on 24 Oct 2011, 1:23 a.m.,
in response to message #1 by dbatiz

The flag 9 is set to true when overflow happen. (HP-15C Owner's Handbook page 45) Thank you.

      
Re: 15C-LE Blinking
Message #4 Posted by dbatiz on 24 Oct 2011, 1:53 a.m.,
in response to message #1 by dbatiz

My apologies. Thank you for the prompt responses. I didnít have my manual handy when I posted the question. I donít remember if the 11C had any blinking error conditions for overflow.

Very respectfully,

David

            
Re: 15C-LE Blinking
Message #5 Posted by MK-52 on 24 Oct 2011, 2:33 a.m.,
in response to message #4 by dbatiz

I checked HP-11C Owner's Handbook (Japanese version). The manual doesn't state the blinking. However, I don't have 11C, and so I cannot check it on real machine.

Edited: 24 Oct 2011, 2:42 a.m.

                  
Re: 15C-LE Blinking
Message #6 Posted by Katie Wasserman on 24 Oct 2011, 10:29 a.m.,
in response to message #5 by MK-52

The 11C doesn't blink on overflow or for any other reason.

                        
Re: 15C-LE Blinking
Message #7 Posted by Nicholas Winterer on 24 Oct 2011, 3:52 p.m.,
in response to message #6 by Katie Wasserman

The blinking feature cost extra, of course.

                              
Re: 15C-LE Blinking
Message #8 Posted by Tim Wessman on 24 Oct 2011, 4:01 p.m.,
in response to message #7 by Nicholas Winterer

How about we make a LE 15c that blinks constantly. That should definitely be worth the price I think you will agree.

TW

                                    
Clairvoyant 15C-LE Blinking
Message #9 Posted by Howard Owen on 24 Oct 2011, 4:18 p.m.,
in response to message #8 by Tim Wessman

Make one that displays your answer before you enter it and you'll have an even bigger hit. :)

                        
Re: 15C-LE Blinking
Message #10 Posted by uhmgawa on 24 Oct 2011, 5:52 p.m.,
in response to message #6 by Katie Wasserman

Quote:
The 11C doesn't blink on overflow or for any other reason.

Technically there is a single BLINK opcode in the 11c rom image, executed just after "running" is loaded into the display registers. Other instances of a 0x030 word are in what appears to be constant data.

[Edit: the same appears true for the 12c/16c firmware versions I've checked.]

Edited: 24 Oct 2011, 6:03 p.m.

            
Re: 15C-LE Blinking
Message #11 Posted by Gerson W. Barbosa on 24 Oct 2011, 4:22 p.m.,
in response to message #4 by dbatiz

No need to apologize. The HP-15C is the only Voyager that blinks on overflows, as far as I know. Cyrille once called this a "strange 15C behavior", perhaps the first indication that the HP-15C LE was on its way to becoming true :-)

Regards,

Gerson.

      
Re: 15C-LE Blinking
Message #12 Posted by Dave Britten on 24 Oct 2011, 8:12 p.m.,
in response to message #1 by dbatiz

You can also manually trigger the blinking display with SF 9, if you have some need to do that in a program (signal an error, or what have you).

            
Re: 15C-LE Blinking
Message #13 Posted by Marcus von Cube, Germany on 25 Oct 2011, 1:57 a.m.,
in response to message #12 by Dave Britten

Yes you can. SF 9 starts blinking, CF 9 stops it. At least on the 15C. I think the 11C doesn't have flag 9. (Just checked it: It has only two flags.)

Edited: 25 Oct 2011, 1:59 a.m.

            
Re: 15C-LE Blinking
Message #14 Posted by Jeroen Van Nieuwenhove on 25 Oct 2011, 3:44 p.m.,
in response to message #12 by Dave Britten

And, curious enough, the blinking behavior can be disabled again not only by entering CF 9, but also by pressing the backspace key, as well as by powering off/on the calculator.

                  
Re: 15C-LE Blinking
Message #15 Posted by uhmgawa on 26 Oct 2011, 10:36 a.m.,
in response to message #14 by Jeroen Van Nieuwenhove

Quote:
And, curious enough, the blinking behavior can be disabled again not only by entering CF 9, but also by pressing the backspace key, as well as by powering off/on the calculator.

That behaviour is intentional given the firmware disposition. The r2d2 display controller will exit blink mode when it sniffs a DISOFF instruction or DISTOG instruction (if toggling to the "off" state). Voyager firmware routinely emits DISOFF/DISTOG instructions during execution to minimize visual chatter due to the flurry of partial display updates it performs. In fact the act of pressing any key will disable blink mode. However the firmware keeps reissuing a DISBLINK instruction in the process of routine display updates until flag 9 is cleared.

                        
Re: 15C-LE Blinking
Message #16 Posted by Miguel Toro on 26 Oct 2011, 12:16 p.m.,
in response to message #15 by uhmgawa

Quote:
In fact the act of pressing any key will disable blink mode.

Well, not any key, as an example, numerical keys do not disable blinking. You have to use backspace or ON/OFF on the 15c.

                              
Re: 15C-LE Blinking
Message #17 Posted by uhmgawa on 26 Oct 2011, 4:45 p.m.,
in response to message #16 by Miguel Toro

Quote:
Well, not any key, as an example, numerical keys do not disable blinking. You have to use backspace or ON/OFF on the 15c.

I believe we're tripping over semantics here.

From the perspective of the r2d2 display hardware, each key press results in a DISOFF instruction being emitted by the firmware which disables blink mode. However this isn't apparent to the user as the firmware reenables blink mode (via a DISBLINK/0x030 instruction) during its routine update of the display when flag 9 is set.

                                    
Re: 15C-LE Blinking
Message #18 Posted by Miguel Toro on 26 Oct 2011, 5:47 p.m.,
in response to message #17 by uhmgawa

Understood now!


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