Calculator or Computer?

I can remember it clearly the day I first was introduced to programming. When I was 11 or so years old I wandered into my father's home office and saw his calculator flashing patterns on its red LED display. I asked him what it was doing and he told me "You don't want to know." I told him, "Yes I do!"

The calculator in question was an HP-67. http://www.rskey.org/detail.asp?manufacturer=Hewlett-Packard&model=HP-67

My father was really wonderful about finding ways for me and my siblings to pursue things we were interested in. As long as my homework was done I could use his HP-67 in the dining room. The calculator came with a wonderful manual which taught programming in a most clear and enjoyable way. The HP-67 uses a Reverse Polish Notation style of arithmetic entry. It also supports a GOSUB and RETURN style of programming like BASIC. The other amazing feature of the HP-67 is a magnetic card reader. This is like a tiny floppy disk drive except that the card just moves straight through the calculator instead of spinning around. The cards are about a half inch in width. This made the HP-67 more of a personal computer than a calculator.