Retro Review: Texas Instruments TI-65
Quick Facts:
Model: TI-65 Technical Analyst
Company: Texas Instruments
Years: 1986-1989
Type: Scientific, Programming
Batteries: 2 x LR44
Operating Mode: AOS
Memory Registers: up to 16 (0-F)
Programming Steps: up to 100
Comes in case
Stopwatch and Timer Included
Features
The TI-65 is a late entry of the Texas Instruments and has the following features:
* Trigonometry, Logarithms, Powers
* Absolute value, integral and fraction part
* DMS and HMS conversions (degrees and hours, respectively, 360° for degrees, 24 hours)
* Eight scientific constants
* Eight conversions (→ (US to SI), INV for ← (SI to US), except Joules/calories which the order is reversed)
* Base conversions to hexadecimal and octal only (unfortunately not binary nor any Boolean algebra)
* Statistics
* Linear Regression
* Storage Arithmetic
* Numeric Integration
* Programming
Scientific Constants (the values stored in the TI-65):
c: Speed of light = 299792458 m/s
g: Earth's gravity = 9.80665 m/s^2
me: Mass of an electron = 9.109534 * 10^-31 kg
e: Charge of an electron = 1.6021892 * 10^-19 C
h: Plank's Constant = 6.626176 * 10^-34 J s
k: Boltzmann's Constant = 1.308662 * 10^-23 J/K
Na: Avogadro's Constant = 6.022045 * 10^23 molecules/mole
R: Gas Constant = 8.31441 J/(mole * K)
The SI units are printed with the constants on the TI-65, which I like.
Conversions:
inches - centimeters
ounces - gallons
gallons - liters
degrees Fahrenheit - degrees Celsius
pounds per inch - Pascals
horsepower - kilowatts
Joules - calories
pounds (* foot) - Newtons
Programming, Integration, and Memory
The TI-65 has 100 programming steps that is shared with the memory register. A register is worth seven programming steps, and the amount of memory registers available decrease as you type in steps. Most programming steps are fully merged, hence 2nd, 3rd, and INV (indicated by a negative sign in the key code) with its key count as one step. However, storage arithmetic takes two steps.
Maximum Number of Memory Registers vs. Maximum Amount of Steps
100 steps: 1 register (R0)
98 steps: 2 registers (R0, R1)
91 steps: 3 registers (R0, R1, R2)
84 steps: 4 registers (R0 to R3)
77 steps: 5 registers (R0 to R4)
In learn mode, the number of steps and the maximum number of registers are on display, along with the programming step.
Memory registers can be protected by the [ 2nd ] (PUM) # sequence.
A full set of programming commands are here:
DSZ: decrement R# and skip if zero
INV DSZ: decrement R# and skip if not zero
x<m: test x < R#
INV x<m: test x ≥ R#
x=m: test x = R#
INV x=m: test x ≠ R#
x>m: test x > R#
INV x>m: test x ≤ R#
LBL and GTO: label (0-9, A-F, F1, F2)
F1 and F2: user keys and labels
PAUSE: pauses execution
SBR: subroutine
INV SBR: return
LIST: display steps stored in memory
Integration: Integration requires R0, R1, and R2 to be protected by PUM 2. In the program, use R1 for x (you are given x in the register to start), end the function with [ = ] [ R/S ]. Calculation: lower [ STO ] 1, upper [ STO ] 2, [ 2nd ] ( ∫dx) n [ R/S ]
Statistics: Clear all protection first by PUM 0. Six registers are used, and a maximum number of programming steps is 63 while statistical data is stored. From the TI-65 manual, the following registers take the following values:
R1 = n * Σxy - Σx * Σy
R2 = n
R3 = Σy
R4 = n * Σy^2 - (Σy)^2
R5 = Σx
R6 = n * Σx^2 - (Σx)^2
Stopwatch and Timer
The TI-65, billed as a technical calculator aimed at professionals, includes a stopwatch and timer (but not a clock).
Stopwatch:
Press [ 3rd ] ( TUp↑) to start the stop watch. Do this again to stop it.
Timer:
Enter the time in hh:mm:ss (hours:minutes:seconds) format, press [ 2nd ] ( TDn↓ ) to start the timer. Do this again to stop it. There are no sounds, the timer displays 00:00:00 when completed.
You can store the timer into any available register. The store key is not required in this instance. Recall the last time by pressing [ RCL ] [ : ].
It may be possible to include the stopwatch and timer, however, they will not run in the background. When the stopwatch or timer is working, the TI-65 is locked out of calculations. Still, a nice feature.
Closing Thoughts
I believe that the TI-65 is the penultimate calculator in the Galaxy series (the last is the TI Galaxy 67). It's one of Texas Instruments' most underrated calculators and production had continued into the 1990s, it could of had served as a non-graphing alternate to the TI-81. Back in the early 1990s, graphing calculators were not as accepted in school; today, they are expected.
If you are collecting calculators, I would recommend the TI-65. It's one of the best keystroke programming calculators Texas Instruments made since the TI 58/59, with a complete set of instructions and a decent amount of memory. You do need a little patience because the TI-65 can be slow (especially compared to today's calculators). The case and the sticker with helpful hints attached to it make a nice touch.
(I don't recall the TI-67 Galaxy ever being on sale in the United States.)
Here are some TI-65 programs I posted in July 2016:
http://edspi31415.blogspot.com/2016/07/ti-65-programs-part-i-digital-root.html
http://edspi31415.blogspot.com/2016/07/ti-65-programs-part-ii-reynolds.html
http://edspi31415.blogspot.com/2016/07/ti-65-programs-part-iii-impedance-and.html
and will have more on tomorrow's post.
Sources:
Texas Instruments. "TI-65 Technical Analyst" http://www.datamath.net/Leaflets/CL-947A_US.pdf Flyer provided by datamath.net. Last accessed April 10, 2022.
Texas Instruments TI-65 Technical Analyst Guidebook 1986
Toth, Viktor. "TI-65" rskey.org. 2022 http://www.rskey.org/ti65 Last Accessed April 29, 2022
Tschnenrechner-Sammlung, Tony "TI-65 Galaxy" Tony's Taschenrechner-Sammlung Calculator Collection https://www.thimet.de/CalcCollection/Calculators/TI-65/Contents.htm Last accessed April 29, 2022
Eddie
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