DM-xxCC Default Display Values


Michael has really improved the look of his web site at 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
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


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.


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....)


I wonder what the keys of the ones with titanium housing will be like!

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