HP 41C and DM41: Operations by Test, Messages, Block Storage
The programs are inspired from a great calculator resource, "Calculator Tips & Routines Especially For The HP-41C/41CV", edited by John Dearing (see source below).
Operations by Test
One of the tips presented is the selection of one of two opposite arithmetic operations based on a comparison between X and Y values. This tip was provided by Bill Kolb (tip 2-7). They are:
X?Y
CHS (subtract if test is true)
+ (add if test is false)
X?Y
1/X (divide if the test is true)
* (multiply if the test is false)
X?Y
1/X (take the root if the test is true)
Y↑X (take the power if the test is false)
The following programs uses the test X<Y:
TESTAS: X<Y (subtract, y - x), X≥Y (adding, y + x)
(^T represent the beginning of an alpha string)
01 LBL^T TESTAS
02 X<Y?
03 CHS
04 +
05 END
Example:
45, 13, XEQ TESTAS returns 32 (45 - 13)
13, 45, XEQ TESTAS returns 58 (13 + 45)
TESTMD: X<Y (divide, y/x), X≥Y (mulitply, y * x)
01 LBL^T TESTMD
02 X<Y?
03 1/X
04 *
05 END
Example:
45, 13, XEQ TESTMD returns 3.4615 ( ≈ 45 / 13)
13, 45, XEQ TESTMD returns 585 (13 * 45)
TESTPR: X<Y (root, y^1/x), X≥Y (power, y^x)
01 LBL^T TESTPR
02 X<Y?
03 1/X
04 Y↑X
05 END
Example:
49, 3, XEQ TESTPR returns 3.6593 ( ≈ 49 ^ 1/3)
3, 49, XEQ TESTPR returns 2.3930E23 (≈ 3 ^ 49)
Messages
With the use of AVIEW during a loop, you can display a loop up to 12 characters while the loop is running. A CLD (clear display) is added after the loop's completion to clear the alpha display and show the stack. (tip 2-25)
The program TESTSUM adds a message while the 41C is summing numbers from 1 to X. While this is not the most efficient way to tackle the problem, this illustrates the use of messages.
01 LBL^T TESTSUM
02 STO 01
03 0
04 STO 02
05 LBL 01 // loop begins
06 RCL 01
07 ST+ 02
08 ^T ADDING... // message
09 AVIEW // display the message
10 DSE 01
11 GTO 01
12 CLD // clear display
13 RCL 02
14 END
Example:
50, XEQ TESTSUM
Display: ADDING..., then 1275
Block Storage
You can use indirect storage and the stack to store a constant in a block of consecutive storage registers. A sample loop:
LBL %%
STO IND Y
ISG Y
GTO %%
Where %% is a label, and the loop variable is B.EEE (B: beginning register, E: ending register) stored in this case, Stack Y. (tip 10-1)
The program LOADBLK, prompts the user enter the value, beginning register number, and ending register number.
01 LBL^LOADBLK
02 ^T VALUE
03 PROMPT
04 STO Z // keystrokes: [ STO ] [ . ] ( Y )
05 ^T R%% BGN?
06 PROMPT
07 ^T R%% END?
08 PROMPT
09 1E3
10 /
11 +
12 STO Y
13 RDN // R↓
14 X<>Y
15 LBL 01
16 STO IND Y // keystrokes: [ STO ] [ shift ] [ . ] ( Y )
17 ^T STORING... // message
18 AVIEW
19 ISG Y // keystrokes: [ shift ] ( ISG ) [ . ] ( Y )
20 GTO 01
21 ^T DONE
22 AVIEW
23 PSE
24 CLD
25 END
Try this:
Store π in R00 to R03 and e^1 in R04 to R07.
Results: (Fix 4)
R00: 3.1416
R01: 3.1416
R02: 3.1416
R03: 3.1416
R04: 2.7183
R05: 2.7183
R06: 2.7183
R07: 2.7183
Source:
Dearing, John. "Calculator Tips & Routines Especially for the HP-41C/41CV" Corvallis Software, Inc. Corvallis, OR. 1981
Link on HP41.org (account needed): http://www.hp41.org/LibView.cfm?Command=View&ItemID=320
Eddie
All original content copyright, © 2011-2020. Edward Shore. Unauthorized use and/or unauthorized distribution for commercial purposes without express and written permission from the author is strictly prohibited. This blog entry may be distributed for noncommercial purposes, provided that full credit is given to the author.
