APF Mark 90
| 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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APF Mark 90
The APF Mark 90 programmable calculator was yet another OEM variant of the Commodore PR-100. (Or was it the other way around?) However, unlike some of the other clones, this one looks quite different. Some of the buttons have different labels (e.g., STO), positions of the sliding program switch are rearranged, and the calculator's visual appearance matches that of other APF calculators of the LED era.
As it turns out, the differences are entirely cosmetic in nature. Internally, the two calculators are identical. A curious difference, however, does exist in the documentation: the Commodore PR-100 has a small manual that contains several example programs. The APF Mark 90's manual contains a number of interesting calculating examples, but none of them are presented in the form of a keystroke program.
The calculators may be identical, but I do have a new Gamma function implementation I wrote after I received this Mark 90. Unlike other implementations, this one does not use a polynomial approximation; instead, it evaluates the incomplete Gamma function. With an integration limit of 24 and an argument between 0 and 1, the result is essentially identical (within the calculator's limit of precision) to that of the Gamma function itself. The incomplete Gamma function is evaluated iteratively; for arguments greater than 1, another iteration is used to arrive at the final result. For most arguments, this program yields at least 8 digits of precision. The downside is that the program is a lot slower than a polynomial approximation.
85 00 − 81 01 1 51 02 STO 81 03 1 55 04 x/y 84 05 + 15 06 SKIP 14 07 GOTO 81 08 1 61 09 7 94 10 +/− 21 11 SHIFT 74 12 M× 81 13 1 14 14 GOTO 91 15 0 83 16 3 81 17 1 55 18 x/y 94 19 +/− 34 20 yx 51 21 STO 82 22 2 82 23 2 71 24 4 55 25 x/y 75 26 ÷ 52 27 RCL 82 28 2 95 29 = 51 30 STO 71 31 4 51 32 STO 83 33 3 74 34 × 82 35 2 71 36 4 75 37 ÷ 81 38 1 21 39 SHIFT 84 40 M+ 82 41 2 52 42 RCL 82 43 2 84 44 + 51 45 STO 83 46 3 52 47 RCL 71 48 4 85 49 - 21 50 SHIFT 55 51 x-M 71 52 4 55 53 x/y 95 54 =/K 94 55 +/− 52 56 RCL 15 57 SKIP 14 58 GOTO 83 59 3 83 60 3 71 61 4 75 62 ÷ 82 63 2 71 64 4 21 65 SHIFT 32 66 ex 74 67 × 52 68 RCL 81 69 1 95 70 =/K
