Found this thread from the Swissmicros DM42 buying thread. My first real calculator was a TI-58C (TI-59 without the card reader) that I bought in 78 and used my first few years of college. That was replaced with a Sharp EL-5100, which was really neat in that you could enter equations in long lines as actually written. It stored in a hard plastic slip case, that led to it's demise when it slipped out of the case that was in my pack and fell to the tile bathroom floor at school, cracking the display (it still worked, but you couldn't read the LCD!) At that point, I broke down and bought a 42S in 88. I had never used RPN before, but what a difference! I have a hard time using a TI now. The 42S lasted until 99 (buttons and display were getting wonky) and it was replaced with a 48G. I still prefer the 42S, but it has been lost (didn't realize how valuable it was!). I too have the Free 42 app on my iPhone and will use that versus pulling out the 48G. I will have to seriously consider the DM42!
TI-58C
Sharp EL-5100
HP42S
HP48G