The Museum of HP Calculators


HEX-DEC / DEC-HEX for the HP-33E

This program is by Glenn Hayhurst and is used here by permission.

This program is supplied without representation or warranty of any kind. Glenn Hayhurst 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.

Overview

This is a program that I wrote around 1978 that I used to convert DECIMAL numbers to HEX numbers when I worked for a company that made mainframe tape drives. One of my manufacturing jobs was to use a wirewrap gun to code the serial number into the backplane of the tape drives in HEX. I had to convert the decimal serial number that was stamped on the frame to a HEX value and then install the wires in the correct places bit by bit. after I wrote the first part of the program I had enough program steps left to write the reverse conversion from HEX to DECIMAL. It all fit within the 49 step limit of the HP-33E.

This program will convert DECIMAL numbers in the range of 0-65535 to their HEX equivalents.

It will also convert HEX numbers in the range of 0-FFFF to their DECIMAL equivalents.

Listing

Key	Display

_______________

ENTER	01-31
RCL 5	02-24 5
/	03-71
g INT	04-32
STO 1	05-23 1
RCL 5	06-24 5
*	07-61
-	08-41
ENTER	09-31
ENTER	10-31
RCL 6	11-24 6
/	12-71
g INT	13-15 32
STO 2	14-23 2
RCL 6	15-24 6
*	16-61
-	17-41
ENTER	18-31
ENTER	19-31
RCL 7	20-24 7
/	21-71
g INT	22-15 32
STO 3	23-23 3
RCL 7	24-24 7
*	25-61
-	26-41
g INT	27-15 32
STO 0	28-23 0
RCL 1	29-24 1
f PAUSE	30-14 74
RCL 2	31-24 2
f PAUSE	32-14 74
RCL 3	33-24 3
f PAUSE	34-14 74
RCL 0	35-24 0
GTO 00	36-13 00
RCL 1	37-24 1   <-Entry point for H>D conversion
RCL 5	38-24 5
*	39-61
STO + 0	40-23 51 0
RCL 2	41-24 2
RCL 6	42-24 6
*	43-61
STO + 0	44-23 51 0
RCL 3	45-24 3
RCL 7	46-24 7
*	47-61
STO + 0	48-23 51 0
RCL 0	49-24 0


Enter the program, then store these three values that are used in the calculations.

4096	STO 5
256	STO 6
16	STO 7


Before running the program for the first time, hit g RTN. This sets the program to step 00.

Example: To convert from DECIMAL to HEX: 43961 ENTER (stores value in Y register) R/S (run program)

The display will pause with four numbers. These numbers appear in the order of the hex value. (See number converstion table below)

	10	11	11	9	(Display shows)
	A	B	B	9	(Hex Value)


Example: To convert from HEX to DECIMAL: Store the hex values in the following registers.
I.E.	(   HEX   )	A	B	B	9
	(DEC equiv)	10	11	11	9


	10	STO 1
	11	STO 2
	11	STO 3
	9	STO 0

Then:	GSB 37	(entry point for H>D conversion)

The program will run converting the values stored in registers 1, 2, 3, 0 to a decimal value that is left in the X register (display).

	Answer:	43961


Number conversion table: HEX DECIMAL --- ------- 0 0 1 1 2 2 ... ... 9 9 A 10 B 11 C 12 D 13 E 14 F 15
Registers used: R0 HEX digit R1 HEX digit R2 HEX digit R3 HEX digit R4 unused R5 4096 fixed value for program R6 256 fixed value for program R7 16 fixed value for program

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