TI65 Programs Part I:
Digital Root, Complex Number Multiplication, Dew Point
Recently working with the HP71B and Radio Shack EC4004, I
am feeling the 1980s vibes and staying in the decade for the 1987 classic
calculator Texas Instruments TI65.
Some background information of the TI65 (provided by
Datamath): http://www.datamath.org/Sci/Galaxy/TI65.htm
Did you know the TI65 has a timer? Click here to see a video demonstration!
This is the first part of programs for the TI65 for this
Fourth of July.
Click here for Part II: Reynold’s Number/Hydraulic Diameter, Escape Velocity, Speed of Sound/Resonant Frequencies in an Open Pipe
Click here for Part II: Reynold’s Number/Hydraulic Diameter, Escape Velocity, Speed of Sound/Resonant Frequencies in an Open Pipe
Click here for Part III: Impedance and Phase Angle of a Series RLC Circuit, 2 x 2 Linear System Solution, Prime Factorization
TI65 Digital Root
Takes the digital root of an integer. To find the digital root:
1. Add up the number’s
digits.
2. The sum is over
10, add the digits again.
3. Repeat step 2
until you get a single digit.
Or alternatively, use the formula dr(n) = 1 + ((n1) mod 9)
= n – 9 * intger((n1)/9)
Program:
CODE

STEP

KEY

12.0

00

STO 0

49

01



9

02

9

38

03

*

16

04

(

16

05

(

13.0

06

RCL 0

49

07



1

08

1

17

09

)

28

10

÷

9

11

9

17

12

)

2^{nd} 27

13

ITNG

14

14

=

51

15

R/S

Input: Enter integer,
press [RST] [R/S]
Test 1: dr(1555) = 7
Test 2: dr(38267) = 8
TI65 Complex Multiplication
(a + bi)*(c + di) = (r1*r2) * e^(i*(θ1 + θ2))
Where r1 ∠ θ1 is the polar form of a + bi
and r2 ∠
θ2 is the polar form of c + di.
Program:
CODE

STEP

KEY

COMMENT

44

00

X<>Y

Start with a

51

01

R/S

Prompt for b

2^{nd} 22

02

INV 2^{nd}
PR

Convert to Polar

12.1

03

STO 1


44

04

X<>Y


12.0

05

STO 0


51

06

R/S

Prompt for c

44

07

X<>Y


51

08

R/S

Prompt for d

2^{nd} 22

09

INV 2^{nd}
PR

Convert to Polar

12.59

10

STO+


1

11

1

STO+ 1

44

12

X<>Y


12.38

13

STO*


0

14

0

STO* 0

13.0

15

RCL 0


44

16

X<>Y


13.1

17

RCL 1


2^{nd} 22

18

2^{nd} PR

Convert to
Rectangular

51

19

R/S

Display imaginary
part of product

44

20

X<>Y


51

21

R/S

Display real part
of product

(a + bi)*(c + di) = x + yi
Input: a [RST] [R/S],
b [R/S], c [R/S], d [R/S]
Output: y [R/S], x
Test 1: (53i)*(4+i):
5 [RST] [R/S]. 3 [R/S], 4 [R/S], 1 [R/S]
Result: 7 [R/S]
23, 237i
Test 2: (6+3i)*(2 +
2i)
Result: 18 – 6i
TI65 Dew Point Calculation
This program accepts input and displays dew point in degrees
Fahrenheit (°F).
Source for
formula: http://ag.arizona.edu/azmet/dewpoint.html
CODE

STEP

KEY

COMMENT

3^{rd} 28

00

3^{rd} °F°C

Convert to °C

12.0

01

STO 0


38

02

*


1

03

1


7

04

7


57

05

.

Decimal Point

2

06

2


7

07

7


12.1

08

STO 1


28

09

÷


16

10

(


2

11

2


3

12

3


7

13

7


57

14

.

Decimal Point

3

15

3


12.2

16

STO 2


59

17

+


13.0

18

RCL 0


17

19

)


59

20

+


51

21

R/S

Prompt for h

32

22

LN


39

23

=


28

24

÷


13.1

25

RCL 1


39

26

=


12.1

27

STO 1


38

28

*


13.2

29

RCL 2


28

30

÷


16

31

(


1

32

1


49

33




13.1

34

RCL 1


17

35

)


39

36

=


3^{rd} 28

37

INV 3^{rd} °F°C

Convert to °F

51

38

R/S

Input: Enter temperature in °F [RST] [R/S], enter
humidity (as a decimal) [R/S]
Output: Dew Point in °F
Test 1: temperature =
68°F, humidity = 0.5 (50%)
68 [RST] [R/S], 0.5 [R/S]
Result: dew point ≈
48.68533155°F
Temp 2: temperature =
93°F, humidity = 0.35
Result: dew point ≈
61.29167421°F
Happy Birthday United States!
This blog is property of Edward Shore, 2016.