HP Forum Archive 21

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DM-xxCC Default Display Values Message #1 Posted by Mark Hardman on 12 Sept 2012, 9:38 p.m. Michael has really improved the look of his web site at http://www.rpn-calc.ch/. The home page now features a carrousel of all five calculator models. Mindlessly spinning the calculators, I started wondering why he chose the various default display values for each model: DM-10CC = 1.7321 Easy, 3 SQRT DM-11CC = 1.4142 Again easy, 2 SQRT DM-12CC = 1.55 The best I that I can come up with is: 111 LN LN DM-15CC = 1.6180 Pure gold, 5 SQRT 1 + 2 / DM-16CC = AA55 H Again, no idea: BIN 1010101 Enter Enter 1001 RLn + HEX or HEX 55 Enter Enter 9 RLn + Does anyone have a better solution for the DM-12CC or DM-16CC? Maybe Michael could give us the real answers. Mark Hardman

Re: DM-xxCC Default Display Values Message #2 Posted by Cristian Arezzini on 13 Sept 2012, 5:22 a.m., in response to message #1 by Mark Hardman About the "AA55": don't think too much about mathematics there, remember it's a programmers' calculator. And "AA" and "55" are two bytes often used for memory testing, as they have a peculiar bit pattern - AA is 10101010 and 55 is 01010101. So it might just be a tribute to old-style computer programming, which is what the 16C was for.

Re: DM-xxCC Default Display Values Message #3 Posted by Dale Reed on 13 Sept 2012, 2:28 p.m., in response to message #2 by Cristian Arezzini It goes back even further than that. In the old Teletype days (Western Union Telex et al), they used to send a line of "RYRYRYRYRYRYRY"... in order to "exercise" the send and receive contacts. These machines use the old 5-level (5-bit) "Baudot" code. R and Y are the TTY equivalent of 0xAA55 for memory tests --- their bit patters are 01010 and 10101 (but I don't remember offhand which is which). They especially look nice punched into paper tape! | o o o o o o o o o | o o o o o o o o | o o o o o o o o o | o o o o o o o o | o o o o o o o o o Dale, W8ABZ (Don't ask how many Teletype (R) Model 19ASR, 28ASR and 32ASR machines I fixed back in the radio club in college days....)

Re: DM-xxCC Default Display Values Message #4 Posted by Lode on 13 Sept 2012, 3:42 p.m., in response to message #1 by Mark Hardman I wonder what the keys of the ones with titanium housing will be like!

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