HP Forum Archive 14

[ Return to Index | Top of Index ]

+/- key on RPN calcs Message #1 Posted by Bill P on 18 May 2004, 3:53 p.m. What was the first HP calc to have a +/- key? Before the +/- key, what was the best way to multiply what was in the x register by a negative number?

Re: +/- key on RPN calcs Message #2 Posted by Dave Shaffer on 18 May 2004, 4:11 p.m., in response to message #1 by Bill P From the beginning (the HP 35) there was the "CH S" (change sign) key - although its operation depended on what keys you had most recently hit. From the Museum description of the HP 35: "The HP-35 allowed the user to press the CHS sign before or during number entry. If a number was in the display as a result of something other than digit entry, pressing CHS negated it, but if the CHS key was then followed by a digit, the calculator assumed the CHS was actually meant for the following entry. Thus the previous number displayed was pushed onto the stack without the (already displayed) sign change. This feature could be confusing and later models required the CHS key to be pressed after the first digit of a number."

Re: +/- key on RPN calcs Message #3 Posted by Dave Shaffer on 18 May 2004, 4:14 p.m., in response to message #2 by Dave Shaffer P.S. "This feature could be confusing and later models required the CHS key to be pressed after the first digit of a number." It was, indeed, confusing. To this day, I still have some trepidation as to what will happen when I hit +/- on my newer (than the HP 35) calculators! Does anybody else share this remembrance (and concern)?

Re: +/- key on RPN calcs Message #4 Posted by Bill P on 19 May 2004, 2:22 a.m., in response to message #2 by Dave Shaffer Silly me. I am, as you have certainly guessed, new to HP calcs. In fact, I've only been using them for 8 years. All I've actually owned are the 48GX and the 33S. Thanks for the correction.

Re: +/- key on RPN calcs Message #5 Posted by Charles Perry on 18 May 2004, 4:18 p.m., in response to message #1 by Bill P The first HP calcs with a +/- key seem to be the 32s and 42s. Before that all HP calcs had a CHS (change sign) key with the same function. The HP35 had a CHS key that functioned a little differently as Dave pointed out in his post. Soooooo, HP calcs have basically always had a way of changing the sign of a number.

Re: +/- key on RPN calcs Message #6 Posted by Charles Perry on 18 May 2004, 4:23 p.m., in response to message #5 by Charles Perry Correction: Looks like the 18C had the first +/- key in 1986. It is odd that the 28C had the CHS key since it is from the same time frame and same platform.

The HP01 in 1977...Re: +/- key on RPN calcs Message #7 Posted by Gene on 18 May 2004, 4:45 p.m., in response to message #1 by Bill P +/- is a shifted function. :-)

Re: The HP01 in 1977...Re: +/- key on RPN calcs Message #8 Posted by marais on 19 May 2004, 3:28 a.m., in response to message #7 by Gene ...but technically, that's not an RPN machine :)

Re: +/- key on RPN calcs Message #9 Posted by Tony Duell on 19 May 2004, 8:17 a.m., in response to message #1 by Bill P Not a handheld, but the very first HP calculator -- the HP9100A -- has a Change Sign key.

Re: +/- key on RPN calcs Message #10 Posted by Gene on 19 May 2004, 10:30 a.m., in response to message #9 by Tony Duell It wasn't really the change sign key, but a specific +/- (instead of a CHS label). :-) Gene

[ Return to Index | Top of Index ]

Go back to the main exhibit hall