PTK-1050

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: 3"×5½"×1½" Display size: 8+2 digits
Weight: 6 oz    
    Entry method: Algebraic with precedence 
Batteries: 2×"AA" NiCd Advanced functions: Trig Exp 
External power: TI AC-9132 adapter (5.7VAC 240mA)   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: Auto-insert program entry  
Chipset: Texas Instruments TI-57   Forensic result:  

ptk1050.jpg (28558 bytes)During a recent trip to Hungary, my wife visited a flea market. That evening when we spoke on the telephone, she told me excitedly that she found some interesting-looking old calculators. One of them had a model number that was a bit faded and hard to read; a PTK... what, 1058? No, it must be a 1050! Yippie! Another rare model, finally located.

I have no idea really how rare the PTK-1050 was, but I certainly didn't encounter it back when it was originally manufactured. It was only much later that I learned about this model number and found out that it was none other but the Texas Instruments TI-57 in disguise (this, in fact, is visible in the picture on the right, as the original Texas Instruments label is faintly revealed under the fading Hungarian overlay.) A good calculator it is, too; its limited program capacity is offset by its fully merged programming model (this was the only early Texas Instruments calculator with this feature) and a well-designed set of program instructions. The only shortcoming is the lack of permanent program storage or continuous memory, making it necessary to re-enter programs every time the calculator is turned off.

Alas, when I powered up this PTK-1050, it was just barely functional. The display came up alright, but half the keyboard was dead, not responding at all to keystrokes. Opening the calculator quickly revealed the cause: the keyboard panel was thoroughly rotten with corrosion.

Fortune intervened. Just recently, I acquired a set of what appeared to be Texas Instruments keyboard panels. And that's indeed what they were: keyboard panels for the TI-59 family of calculators. The good news is that these keyboard panels are essentially identical to those used in the TI-57, except for an extra row of keys at the top. This row of keys can be carefully removed without damaging the connecting wires or the remainder of the keyboard. Which is exactly what I did, and after less than an hour of surgery, I had a fully functional PTK-1050 in my hands.

The program below demonstrates the power of this calculator by implementing the Gamma function using the Lanczos-approximation, computing the logarithm of the Gamma function to the maximum achievable precision for all positive arguments.

M0=2.5066282835
M1=92.207048452
M2=-83.177637083
M3=14.802831931
M4=-0.22084970795
00  86 0   LBL 0
01  38 1   EXC 1
02  45     ÷
03  38 1   EXC 1
04  32 5   STO 5
05  75     +
06  33 0   RCL 0
07  75     +
08  33 2   RCL 2
09  45     ÷
10  01     1
11  34 5   SUM 5
12  33 5   RCL 5
13  75     +
14  33 3   RCL 3
15  45     ÷
16  01     1
17  34 5   SUM 5
18  33 5   RCL 5
19  75     +
20  33 4   RCL 4
21  45     ÷
22  01     1
23  34 5   SUM 5
24  33 5   RCL 5
25  85     =
26  13     ln
27  75     +
28  43     (
29  33 5   RCL 5
30  65     -
31  03     3
32  83     .
33  05     5
34  44     )
35  55     ×
36  43     (
37  33 5   RCL 5
38  75     +
39  83     .
40  08     8
41  05     5
42  44     )
43  32 5   STO 5
44  13     ln
45  65     -
46  33 5   RCL 5
47  85     =
48 -61     INV SBR