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
Years of production:   Display type: Numeric display  
New price:   Display color: Red  
    Display technology: Light-emitting diode 
Size: 5½"×3"×1½" Display size: 8+2 digits
Weight: 6 oz    
    Entry method: Algebraic with precedence 
Batteries: 2×"AA" NiCd Advanced functions: Trig Exp Sdev 
External power: AC-9132 adapter (5.7VAC 240 mA)   Memory functions: +/-/×/÷ 
I/O:      
    Programming model: Fully-merged keystroke entry 
Precision: 11 digits Program functions: Jump Cond Subr Lbl  
Memories: 8 numbers Program display: Keycode display  
Program memory: 50 program steps Program editing: Insert/delete capability  
Chipset:   Forensic result: 9.0047463834  

ti57.jpg (23776 bytes)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
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