Tell me about the HP 67

[Jim Horn]

I second Maximilian's praise of the HP-67. I bought one as soon as they hit the market in 1976 and used it heavily until the HP-41 replaced it in 1979. While it's 26 registers and 224 program steps along with volatile memory (OFF erased everything) is woefully obsolete today, the card reader helped a lot. And in the 1970s it was truely remarkable.

The three shift keys resulted in a busy set of keyboard labels but they were well done and made it easy to use. Before long I was programming it by feel, sometimes while driving between the Los Angeles basin to the San Francisco Bay area at night in the middle of nowhere to keep my mind alert. No menus at all, just shifted keys. And LEDs so I could see the results in the dark.

Combined with its built-like-a-brick ruggedness and two hardware modifications - a 2x speedup control switch and a "phase 0 interrupt" flush button that allowed creation of any desired internal bit pattern - it was a wonderful tool. That latter capability allowed creation of controlled bit pattern magnetic cards which, when read into the HP-41, allowed analysis of the internal operation of that newer machine. One weekend of about ten thousand keystrokes revealed a lot back then...