Launch year
Calculators launched 1975 to 1979
The red LED years. HP's Woodstocks, the HP-25, HP-27 and HP-29C, launched between 1975 and 1977 on rechargeable two-cell packs, and the Spice HP-34C followed in 1979. TI answered with the TI-58 and TI-59 in 1977 and the TI-58C in 1979. The same year the HP-41C arrived with an LCD and four ports, the start of the next era. Calculators from these years are the oldest here, so plan on a new battery pack for the LED models, never run one on its charger without a pack, and check the battery contacts, which break off on Woodstocks.
7 calculators we cover.
HP
RPN programmableHP-41C
- Launched
- 1979
- Entry and display
- RPN · LCD
- Features
- Programmable · Keeps memory · Mag cards · Plug-ins
$200–$400 typical ask
23 on eBay
HP
RPN programmableHP-25
- Launched
- 1975
- Entry and display
- RPN · LED
- Features
- Programmable
$170–$310 typical ask
23 on eBay
HP
RPN scientificHP-27
- Launched
- 1976
- Entry and display
- RPN · LED
$370–$460 typical ask
4 on eBay
HP
RPN programmableHP-29C
- Launched
- 1977
- Entry and display
- RPN · LED
- Features
- Programmable · Keeps memory
$440–$450 typical ask
1 on eBay
HP
RPN programmableHP-34C
- Launched
- 1979
- Entry and display
- RPN · LED
- Features
- Programmable · Keeps memory
$370–$380 typical ask
1 on eBay
Texas Instruments
Algebraic programmableTI-59
- Launched
- 1977
- Entry and display
- Algebraic · LED
- Features
- Programmable · Mag cards · Plug-ins
$80–$160 typical ask
10 on eBay
Texas Instruments
Algebraic programmableTI-58C
- Launched
- 1979
- Entry and display
- Algebraic · LED
- Features
- Programmable · Keeps memory · Plug-ins
$40–$85 typical ask
9 on eBay