Hp-21 a constant companion !
I bought my HP-21 shortly after i saw it in Machine Design magazine in 1976. From then on it became my constant companion until appx 1995 or so when it gave up the ghost and would no longer illuminate. Much later on I was overjoyed to find an e-version replica of my faithful pocket resource, though he was no longer needed after I retired from field work. Today I have switched to Android apps and regret that I cannot find a replica of this trusty device,,,,, and would like to ask IF THERE IS ONE (?) or one under development? All iOS products havre become too expensive and unreliable !
Show more
50 years later - Thank you
Many thanks for giving me the opportunity to use this RPN calculator. I bought my very first HP 21 C in 1972 when studying at Polytechnic School of Cameroon. 50 years later, I am still very happy and proud using RPN devices and programming Common LISP.
Hate that high visibility setting
To me, the value of this app (and all the other RPN apps that I have) is the authenticity of them. Otherwise, there are a gazillion calculators with different sized displays out there with RPN.
Instead of making the X view high visibility, why not enlarge the calculator itself to be full screen (even getting rid of the stack view optionally)
Then I’ll go back to 5 stars again which otherwise this app absolutely deserves.
Instead of making the X view high visibility, why not enlarge the calculator itself to be full screen (even getting rid of the stack view optionally)
Then I’ll go back to 5 stars again which otherwise this app absolutely deserves.
Show more
Response from developer
For some thoughts on sizing, see: https://www.bigcatos.com/BigCatOs/go-2x-scirpn/go-21sizehistory.html The App seems to be sized as authentically as possible. The stack view is and always has been optional, simply hide it forever, as described in the documentation. The High Visibility Display setting is optional and disabled by default so you never have to see it, thus the calculator remains in its pristine state. This option has been requested by two groups of users: as an Accessibility assist for those with diminished vision, and folks who use the App outdoors as part of their work.
Lean & Mean
I’ve been using this app for a number of years and have been very satisfied and figured it was time I gave it a review. As an engineer, I loved my HP-21 and was sad when it finally died many moons ago. I searched and searched for a simple reverse Polish calculator app, but could never find a good one. This is a good one. A clean but elegant emulation of a classic design. Highly recommended.
Show more
My thoughts on the HP 21 app
I have an hp 21 that we purchased new and I've always loved it, not only for the RPN feature but for the simplicity. This is such a nice app for anyone familiar with the HP line plus it shows the stack. Highly recommend.











