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

Yes. It is normal.

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

My apologies. Thank you for the prompt responses. I didn’t have my manual handy when I posted the question. I don’t remember if the 11C had any blinking error conditions for overflow.

Very respectfully,

David

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.

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

The blinking feature cost extra, of course.

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

TW

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

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.

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

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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.

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).

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.

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.

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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.

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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.

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

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

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

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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.

Understood now!