Texas Instruments TI-57
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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The TI-57 is a mid-range programmable calculator that belongs to the same family as the TI-55, and can be considered a successor of the SR-56. It was the first calculator from Texas Instruments that offered a fully merged keystroke programming model: operations that required as many as four keystrokes (e.g., INV 2nd Prd 0) now fit into a single program step. The calculator relied on label addressing for control transfer; this and some other characteristics of its programming model strongly suggests that the engineers at Texas Instruments took notice of Hewlett-Packard's programmable models.
Despite the meager size (50 steps) of its program memory, keystroke merging made the TI-57 a very versatile tool. I find the limited number of data registers a more severe constraint. Only 8 registers are available, and these are liberally used by many of the calculator's built-in functions. For instance, the t-register was mapped to register 7, precluding the simultaneous use of both; registers 6 and 5 were used for pending operations when evaluating complex expressions. These "features", for lack of a better term, made programming on the TI-57 more of a chore than it needed to be.
Despite these problems, I found it possible to cram a Gamma function program with 7-digit accuracy into the calculator's limited program memory. When entering the program, you must set the contents of registers 2-7 to the listed values (this needs to be done only once.) To enter constants that are accurate to the calculator's 10 digits of internal precision (as opposed to the 8 digits of the display) use a technique like this:
8.2784822 ÷ 10 + 68 = STO 3
.9596084 + 755 = STO 4
To use the program, enter a positive real argument and key SBR 0.
Incidentally, the length of this program makes it possible to add the two program steps necessary to put the TI-57 into "constant memory" mode, as described on the home page of Gene Wright. Briefly, you need to enter the two steps with the following keystrokes: GTO 2nd 4 8 LRN 2nd Exc SST 2nd Lbl 1. To put the calculator in sleep mode, enter CLR GTO 2nd 4 8 R/S INV STO 3 +/- +/-. To exit sleep mode enter INV 2nd Fix CLR.
M2=√2π
M3=68.82784822
M4=755.9596084
M5=4151.488796
M6=11399.36541
M7=12520.43913
00 86 0 LBL 0
01 32 0 STO 0
02 32 1 STO 1
03 33 2 RCL 2
04 39 0 PRD 0
05 33 3 RCL 3
06 34 0 SUM 0
07 33 1 RCL 1
08 39 0 PRD 0
09 33 4 RCL 4
10 34 0 SUM 0
11 33 1 RCL 1
12 39 0 PRD 0
13 33 5 RCL 5
14 34 0 SUM 0
15 33 1 RCL 1
16 39 0 PRD 0
17 33 6 RCL 6
18 34 0 SUM 0
19 33 7 RCL 7
20 45 ÷
21 33 1 RCL 1
22 85 =
23 34 0 SUM 0
24 05 5
25 38 0 EXC 0
26 86 1 LBL 1
27 45 ÷
28 01 1
29 34 1 SUM 1
30 33 1 RCL 1
31 56 DSZ
32 51 1 GTO 1
32 55 ×
33 83 .
34 05 5
35 34 1 SUM 1
36 33 1 RCL 1
37 23 0 STO 0
38 35 yx
39 05 5
40 -34 1 INV SUM 1
42 33 1 RCL 1
43 45 ÷
44 33 0 RCL 0
45 -13 INV lnx
46 85 =
47 -61 INV SBR