Good grief but typing out the bug ridden code from computer magazines was such a bind and then the ruddy tape stretched and you lost ALL that work... but only after an hour of 10-15 minute attempts to get it to record only to get an error...
... and my son complained about a "slow" 5 second load up time for a game!! Young people today... I tell ye'
Jan Lukasiewicz created the original Polish notation in 1920.. Other scientists recreated it into the Reverse Polish notation a few decades later. I don't know why Hewlett Packard used the RPN in their calculators, but indeed you had to change your "chip" if you came from a conventional notation ,as used by TI, Casio and others.
That HP41c wasn’t my first programmable calculator. Before I had a HP25. Fifty years ago already !. Suddenly I feel quite depressed.
See below a ”program” for the HP25. You had a maximum of 49 steps or lines for the whole program. With this huge amount of memory, the programs were entered tipping them in the keyboard. No need for nasty devices such as tape recorders or, God forbid, floppy disks ..