Hewlett Packard HP-25
The HP-25 started on the drawing board as a scientific calculator with a much larger set of functions than the HP-21. By the time it was done, it was that and it was programmable with 49 lines of memory, making it the least expensive and smallest of HP's programmable calculators. Like the HP-65, the HP-25 caused disbelief in many. It seemed much too small to do so much. Unlike previous programmables, the HP-25 had fully merged key steps... (All multi-keystroke entries like f COS and STO * 2 took a single step.) Engineering display mode was also a first on this calculator.
Like the HP-55, the HP-25 used line number addressing rather than labels. This made it very easy to move around while editing a program but inserting an instruction required either clever coding or reentering all instructions from that point onward. (See the programming page for more information.)
Programs supplied included plotting, base conversions, simultaneous equations in two unknowns, mortgage loan, discounted cash flow, great circle navigation, Newton's method solution to f(x)=0, numerical integration, a random number generator, power curve fit, and games including a moon landing simulator. You could do a lot in 49 steps.
The owner's handbook ends with:
Kindly donated by Stuart Cook and complete with the original packaging, manual and HP Battery Charger. Serial number 1703520057
Manufacturer: Hewlett Packard
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This exhibit has a reference ID of CH33405. Please quote this reference ID in any communication with the Centre for Computing History.