Hewlett Packard HP-75C
Released:September 1982
Weight:1.5 lb / 737 g
Size:10" X 5" ( 25 X 12.5 cm)
CPU:HP 8-bit (Capricorn)
RAM:24K, 16K user
Display:32 character LCD
Storage:1.4K magnetic cards
3 ROM/RAM ports
Power:3 nicad AA cells

By 1982, Hewlett-Packard had made dozens of calculators, even programmable calculators, but the HP-75C is their first handheld portable computer. It's not their first computer though, that would be the HP-85 from 1980, two years earlier.

The BASIC programming language is built-in, as well as a clock and appointment alarm.

There is no built-in permanent data storage, but small magnetic cards can be used to load and save data. On the lower right face of the 75C is the card reader - just a slot where the tiny card is manually inserted and pulled out the right side by the user.

On the front are three expansion slots for tiny RAM or ROM cartridges to be inserted - additional user memory or applications can be added quickly and easily. The "C" in HP-75C is for "continuous memory" - it can access 120K total memory.

On the back is the HP-IL serial interface for external printers, data storage, and other devices.

Here is another HP-75, but disguised as the "AT&T Information Systems" computer, resting in the HP-82718A expansion pod. The pod (originally $875) has 64K additional system memory, a 300 baud modem, and software to support a light-pen (there is a light-pen port on the back of the computer).

Because of the light-pen option, this is not an HP-75C, it's an HP-75D (released in February 1984 for $1095).

Related Links

  • HP-75 from old-computers.com
  • HP-75C from R/S Programmable Calculators
  • HP-75 from hp.com.
  • "Reverse-Engineering the HP-75C"
  • "My collection of HP calculators"
  • HP-75C/D from The Museum of HP Calculators

  • History of Hewlett-Packard Computers

    • 1972: Hewlett-Packard pioneers the era of personal computing with the first scientific hand-held calculator, the HP-35, which makes the engineer's slide rule obsolete.
    • 1973: Stephen Wozniak joins HP.
    • 1976: Steve Wozniak proposes that HP create a personal computer. He is rejected.
    • 1976: October - Steve Wozniak remains at HP, but is soon convinced that he should leave and join Apple Computer.
    • 1976: HP begins Project Capricorn, to build a computer-like calculator.
    • 1980: January - HP completes work on the Capricorn project, producing the HP-85. With a 32-character wide CRT display, small built-in printer, cassette tape recorder, and keyboard, it sold for US$3250.
    • 1980: February - HP announces that it will switch to Japanese makers of 16K RAM chips. HP had examined chips from Japan and the US, and found that chips from the best American firm had six times the failure rate of the worst Japanese producer.
    • 1982: HP introduces the HP-75C portable computer. Price is US$995.
    • 1983: June - HP introduces the HP-7475A 6-pen plotter, for US$1895.
    • 1983: October - HP unveils the HP 150 microcomputer.
    • 1984: May - HP introduces the HP 110 laptop computer.
    • 1984: HP introduces the LaserJet laser printer, featuring 300dpi resolution, for US$3,600
    • 1987: HP releases the HP PaintJet color inkjet printer
    • 1989: May - HP buys workstation maker Apollo Computer for US$476 million.
      Source: Chronology of Events in the History of Microcomputers

    Return to the Obsolete Technology Homepage