Re: HP 33S help Message #16 Posted by Vieira, Luiz C. (Brazil) on 22 Jan 2005, 7:07 p.m., in response to message #3 by Clay Smith
Hi, Clay;
the problem is that you are taking an RPL-based calculator (HP48GGX) and comparing with an RPN-based calculator (HP33S). You see, the HP48GX has an input line (also called command line), where you can key in any user-valid object. Try this in your HP48GX:
1 [ENTER]
You see that only the number 1 is in the stack level 1, right? Press [ENTER] again and you'll see a copy of it in level 2 as well. OK, OK, you'll tell me that a DUP command is performed when there is no "active" input line and you press [ENTER] in the HP48GX, right? And this is true! Press [ENTER] with nothing in the stack and a DUP error message appears in the HP48GX.
The HP33S has no input line, so pressing ENTER performs the ENTER function, also programmable (there is no [ENTER] command or function in the (user)RPL structure; in the HP48GX, ENTER is an operation and cannot be part of an object). Everythime you key in a number in the HP33S it is already being placed in the X-register. To key in an object in the HP48GX (or any other RPL-based calculator) you should key it in the input line first and then press [ENTER] to 'push it up' into the stack.
That's why a copy of any number already in the X-register is sent to the Y-register when you press [ENTER] in the HP33S. In fact, in an RPN-based calculator, [ENTER] performs three actions:
1 - ends (finishes) number entering (when keyed in by the keyboard)
2 - "pushes" stack contents up and copies X-contents into Y-register
3 - disables stack auto-lift so the next entry (either with the keyboard or with a RCL) overwrites the contents of the X-register
The third action becomes concise when you remember that a 'safe' copy of the X-contents is already available in the Y-register. The only loss is T-contents.
I think this sentence of yours makes sense, now: Quote: For some reason, when I put a number into the X stack, it also forces the number into the y stack. So any number I press followed by enter, it goes into my X and Y stack.
Please, feel free asking again. For now, I'd suggest having a brief with the HP33S User's Manual, chapter 2, pages 2-5 to 2-7. If you think you need a bit more, chapter 2 is only 14 pages long.
Best regards.
Luiz (Brazil)
Edited: 22 Jan 2005, 7:13 p.m.
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