Hewlett-Packard HP-25
Datasheet legend
Ab/c:
Fractions calculation
AC: Alternating current BaseN: Number base calculations Card: Magnetic card storage Cmem: Continuous memory Cond: Conditional execution Const: Scientific constants Cplx: Complex number arithmetic DC: Direct current Eqlib: Equation library Exp: Exponential/logarithmic functions Fin: Financial functions Grph: Graphing capability Hyp: Hyperbolic functions Ind: Indirect addressing Intg: Numerical integration Jump: Unconditional jump (GOTO) Lbl: Program labels LCD: Liquid Crystal Display LED: Light-Emitting Diode Li-ion: Lithium-ion rechargeable battery Lreg: Linear regression (2-variable statistics) mA: Milliamperes of current Mtrx: Matrix support NiCd: Nickel-Cadmium rechargeable battery NiMH: Nickel-metal-hydrite rechargeable battery Prnt: Printer RTC: Real-time clock Sdev: Standard deviation (1-variable statistics) Solv: Equation solver Subr: Subroutine call capability Symb: Symbolic computing Tape: Magnetic tape storage Trig: Trigonometric functions Units: Unit conversions VAC: Volts AC VDC: Volts DC |
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Hewlett-Packard HP-25
Even before I acquired a working HP-25 specimen, I was already able to experiment with this wonderful small calculator thanks to an amazing Java simulator. To use, wait for the R/S button to appear on the left (you're downloading about 140 kB of data), and then click on it. If your browser supports Java, the calculator will appear. (This HP-25 simulator was written by Larry Leinweber and placed in the public domain. Calculator image is courtesy of The Museum of HP Calculators.) This version of the simulator is preprogrammed with the program shown below; however, you can use it for any other purpose if you clear the program (f PRGM) and registers (f REG).
Introduced shortly after the HP-65, the HP-25 was another source of amazement to its fans. Despite the much lower price, it was also a programmable calculator, with 49 program steps and 8 memory registers. Program steps were fully merged, so the HP-25's 49 steps were nearly equivalent to the 100 steps of the HP-65.
The simulator is sufficiently reliable and accurate to do some programming. This is how I was able to develop yet another implementation of the Gamma function. This program is of a somewhat reduced precision, which was the only way to make it fit within the calculator's limited program memory; in fact, this implementation is very similar to the one I wrote for the TI-57, showing that these calculators are pretty much in the same league.
To use the program, load it into memory and also initialize registers 2-7. Then, enter the argument and hit the R/S button.
M2=√2π M3=68.82784822 M4=755.9596084 M5=4151.488796 M6=11399.36541 M7=12520.43913 01 23 00 STO 0 02 23 01 STO 1 03 24 02 RCL 2 04 23 61 00 STO× 0 05 24 03 RCL 3 06 23 51 00 STO+ 0 07 24 01 RCL 1 08 23 61 00 STO× 0 09 24 04 RCL 4 10 23 51 00 STO+ 0 11 24 01 RCL 1 12 23 61 00 STO× 0 13 24 05 RCL 5 14 23 51 00 STO+ 0 15 24 01 RCL 1 16 23 61 00 STO× 0 17 24 06 RCL 6 18 23 51 00 STO+ 0 19 24 07 RCL 7 20 24 01 RCL 1 21 71 ÷ 22 23 51 00 STO+ 0 23 05 5 24 31 ENTER 25 01 1 26 23 51 01 STO+ 1 27 41 - 28 24 01 RCL 1 29 23 71 00 STO÷ 0 30 21 x-y 31 15 61 x!=0 32 13 25 GTO 25 33 24 01 RCL 1 34 73 . 35 05 5 36 51 + 37 31 ENTER 38 32 CHS 39 15 07 ex 40 21 x-y 41 31 ENTER 42 31 ENTER 43 05 5 44 41 - 45 14 03 yx 46 61 × 47 24 00 RCL 0 48 61 ×