The Museum of HP Calculators


Date of Easter for the HP-11C/15C/34

This program is by P. J. Schüngel and is used here by permission.

This program is supplied without representation or warranty of any kind. P. J. Schüngel 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

Calculates date of Easter Sunday for any given year after 1583 (assuming gregorian calendar in that place) Ex. 1.4.1888, 6.4.1947, 18.4.1954, 26.3.1967, 31.3.2222, 3.4.2067, 12.4.1936, 12.4.1925, 20.4.2025, 12.4.2020

Input
Year in the format yyyy
Output
Easter sunday in format dd.mm. Can be sligthly shortened to show days after 0 March

Labels/Routinen
LBL C main programme, LBL E for MOD routine (x = y MOD x conserving z and t)

Registers/Flags
REG 8 for year, Flag 3 for D=28 check
Spec. remarks
TEST 5 is x=y on the 11C or 34C

Listing

000- 
001- LBL C
002- STO 8
003- FIX 2
004- SF 3
005- 2
006- 10^x
007- 
008- INT
009- 8
010- x<>y
011- *
012- 2
013- LASTX
014- 3
015- *
016- 3
017- +
018- 4
019- 
020- INT
021- -
022- LASTX
023- 1
024- 5
025- +
026- R^
027- 1
028- 3
029- +
030- 2
031- 5
032- 
033- INT
034- -
035- x<>y
036- RCL 8
037- 5
038- *
039- 4
040- 
041- INT
042- +
043- 7
044- GSB E
045- 7
046- x<>y
047- -
048- RCL 8
049- 1
050- 9
051- GSB E
052- 1
053- 9
054- x<>y
055- *
056- LASTX
057- x<>y
058- R^
059- +
060- 3
061- 0
062- GSB E
063- 2
064- 8
065- TEST 5
066- CF 3
067- Rv
068- x<>y
069- 1
070- 1
071- 
072- INT
073- F? 3
074- CLX
075- x<>y
076- 2
077- 9
078- x<>y
079- 
080- LASTX
081- Rv
082- 1/x
083- INT
084- +
085- R^
086- x<>y
087- -
088- 2
089- 1
090- +
091- -
092- LASTX
093- x<>y
094- CHS
095- 7
096- GSB E
097- 7
098- .
099- 0
100- 3
101- x<>y
102- -
103- +
104- 3
105- 1
106- .
107- 9
108- 9
109- x<>y
110- x<=y
111- RTN
112- x<>y
113- -
114- 1
115- +
116- RTN
117- LBL E
118- 
119- LASTX
120- x<>y
121- FRAC
122- *
123- RND
124- RTN

Shorter version showing only days after 0 March (ie 32 = 1 Apr etc)
000- 
001- LBL C
002- STO 8
003- FIX 2
004- SF 3
005- 2
006- 10^x
007- 
008- INT
009- 8
010- x<>y
011- *
012- 2
013- LASTX
014- 3
015- *
016- 3
017- +
018- 4
019- 
020- INT
021- -
022- LASTX
023- 1
024- 5
025- +
026- R^
027- 1
028- 3
029- +
030- 2
031- 5
032- 
033- INT
034- -
035- x<>y
036- RCL 8
037- 5
038- *
039- 4
040- 
041- INT
042- +
043- GSB 9
044- RCL 8
045- 1
046- 9
047- GSB E
048- 1
049- 9
050- x<>y
051- *
052- LASTX
053- x<>y
054- R^
055- +
056- 3
057- 0
058- GSB E
059- 2
060- 8
061- TEST 5
062- CF 3
063- Rv
064- x<>y
065- 1
066- 1
067- 
068- INT
069- F? 3
070- CLX
071- x<>y
072- 2
073- 9
074- x<>y
075- 
076- LASTX
077- Rv
078- 1/x
079- INT
080- +
081- R^
082- x<>y
083- -
084- 2
085- 1
086- +
087- -
088- LASTX
089- x<>y
090- CHS
091- GSB 9
092- +
093- RTN
094- LBL 9
095- 7
096- GSB E
097- 7
098- x<>y
099- -
100- RTN
101- LBL E
102- 
103- LASTX
104- x<>y
105- FRAC
106- *
107- RND
108- RTN

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