2. The Woodstock Series (1975 - 1979)
	HP 21 Introduced on February 1, 1975, a month after the HP 55, this was an inexpensive alternative to the Classic Series. It was non-programmable, smaller in size and the only calculator that used a switch to select Degrees or Radians mode. Code name: Pumpkin. Original price: $125
	HP 22 This was the business counterpart of the HP 21. Not a programmable calculator, but had 10 registers and the i PMT PV FV business functions found in all HP business calculators by now. Introduced on August 1, 1975. Code name: Turnip. Original price: $165
	HP 25 Introduced on August 1, 1975, six months after the HP 21, this was the first really powerful calculator with a 49-step programmable memory and 8 data registers. It became very popular, especially among people who could not afford the HP 65.  Code name: Squash. Original price: $195 This calculator has a special value to me, as it was my first ever HP. I acquired it in 1975, just as I was graduating high school. I want to thank my father for spending the - then - exorbitant amount of $195 to make me happy. The moment I received my first HP has been etched in my memory for eternity.
	HP 27 The fourth calculator in the Woodstock series, introduced on May 1, 1976. A calculator with unique financial functions was replaced by the HP 27S about 12 (!) years later. Code name: Salad. Original price: $200
	HP 25C Introduced on July 1, 1976, it was an exact replica of the HP 25, but with continuous memory. However, it was the first time in history that HP calculator users could turn their computers off without losing the contents of the memory. Code name: Squish. Original price: $200
	HP 29C Introduced on July 1, 1977, this was the last model of the Woodstock series. It was an improved model of the HP 25C, also with continuous memory. Code name: Bonnie. Original price: $195

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