This program is Copyright © 1978 by HewlettPackard and is used here by permission. This program was originally published in "HP33E Student Engineering Applications".
This program is supplied without representation or warranty of any kind. HewlettPackard Company and The Museum of HP Calculators therefore assume no responsibility and shall have no liability, consequential or otherwise, of any kind arising from the use of this program material or any part thereof.
This program calculates the total resistance of a group of resistors arranged in parallel or in series.
Formulas used:
Resisters in series: R_{T} = R_{1} + R_{2} + R_{3} ... + R_{n} Resisters in parallel: R_{T} = 1/(1/R_{1} + 1/R_{2} + 1/R_{3} ... + 1/R_{n})
Note that this program can be used for summing capacitors in parallel or series instead of resisters. For series capacitors, use the instruction for parallel resistors. For parallel capacitors, use the instructions for series resisters.
Several more advanced programs for circuit analysis may be found in: Anderson, L.H. "CalculatorAided Circuit Analysis," Ham Radio Magazine, pp. 3846, October 1977. Although written for the HP25, they will work equally well on the HP33E/C.
Step 
Instructions 
Input Data/Units 
Keys 
Output Data/Units 
1 
Enter program 

2 
Initialize 

f REG f PRGM 

3 
a) Set for parallel resistors or 

R/S 
0.0000 
b) Set for series resistors 

GSB 03 
1.0000 

4 
Optional: Retrieve last R_{T} for use in next calculation. 

Roll dn 
Previous R_{T} 
5 
Input individual resistor values (Repeat until all resistors have been input.) 
R_{i} 
R/S 

6 
Calculate total resistance of the group 

GSB 12 
R_{T}, ohms 
7 
Optional: Store R_{T} for use in next calculation 
R_{T} 
STO 2 

8 
Go to step 3a or 3b for next group. 

Determine the total resistance from A to B.
Keystrokes Display Comment f REG f PRGM Group 1: R/S 0.0000 Parallel mode 680 R/S 120 R/S GSB 12 102.0000 R1, ohms Group 2: GSB 03 1.0000 Series mode Roll dn 102.0000 Retrieve R1 R/S 330 R/S 680 R/S GSB 12 1,112.0000 R2, ohms Group 3: R/S 0.0000 Parallel mode Roll dn 1,112.0000 Retrieve R2 R/S 220 R/S GSB 12 183.6637 R3, ohms STO 2 Save R3 Group 4: R/S 0.0000 Parallel mode 680 R/S 470 R/S GSB 12 277.9130 R4, ohms (Total R) GSB 03 1.0000 Series mode Roll dn 277.9130 Retrieve R4 R/S RCL 2 R/S GSB 12 461.5767 RT, ohms
LINE CODE KEYS 00 f CLEAR PRGM 01 0 0 02 13 04 GTO 04 03 1 1 04 23 0 STO 0 05 74 R/S 06 24 0 RCL 0 07 15 71 g X=0 08 12 20 GSB 20 09 22 Roll dn 10 23 51 1 STO + 1 11 13 05 GTO 05 12 24 1 RCL 1 13 24 0 RCL 0 14 15 71 g X=0 15 12 20 GSB 20 16 34 CLx 17 23 1 STO 1 18 22 Roll dn 19 13 00 GTO 00 20 22 Roll dn 21 15 3 g 1/x 22 31 ENTER 23 15 12 g RTN
R0 Code: 0 or 1 R1 R, 1/R
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