Navigation Module



#16

HP 41C with Nav - Time and X Modules

Why was I the only bidder on this auction? Not only does the unit come with the Nav, x-functions, and time modules but it has the QUAD memory module too, with all manuals! I have always wanted a navigation module and thought this was a good buy considering that one sold recently for $125.

Considering the high prices for recent sales of the 15C (I got one in excellent shape at a garage sale last year for $5), am I missing something?

Jeff


#17

Congrats, very nice item for a low price:-)

Why you were the only bidder: Maybe because the seller did not look at his watch when starting the auction. At 13:30 many people may just have gotten tired from eating;-)

HTH


#18

Thanks! I thought so. One constraint may have been the US only shipping policy of this seller that would certainly limit the bidder pool significantly. I live in Canada but used a friend's address in the US for shipping.

I look forward to having a spare 41C too!

Regards,

Jeff Kearns

#19

Jeff --

Congratulations on purchasing a great bargain for a collector! Looks to be a non-tallkeys HP-41C, like mine from 1980. A few years ago, I probably would have competed in the auction, but I have all the main pieces of the full ensemble shown.

Your new HP-41C with Quad Memory, Time Module, and Navigation Pac is able to run Tom Sherman's 1985 celestial locator application program for navigation, which I have loaded on my HP-41's. Given the local lat/lon and the UTC time and date, it will identify the position in the sky of the sun, moon, Venus, Mars, Jupiter, Saturn, and a broad selection of stars useful for navigation -- in short, all the celestial objects supported by the Nav Pac.

Each calculation takes several minutes, but it's never wrong...

The X-Functions module provides some backup storage and other useful functions, but you might want X-memory modules as well.

-- KS


Edited: 17 Oct 2010, 11:12 p.m. after one or more responses were posted


#20

Karl,

Thanks for your post! I actually work for a company that makes ECDIS (Electronic Chart Display and Information Systems) products for warships and submarines, although my background in the navy was primarily in marine engineering. I have always had an interest in navigation and astronomy and have played around with the Nav Pac on my Palm-based P41CX. It should be an interesting exercise to run Tom Sherman's 1985 celestial locator application program for navigation - when I find it!!!

So far, I found reference to it in an old post here, in which you participated: Tom Sherman's Celestial Locator Post

If I cannot find it on my own, I will be in touch.

Regards,

Jeff


#21

Jeff --

Geir Isene modified the program to provide a quicker, more compact user interface. I then inserted a single valuable instruction.

I possess the full hardcopy documentation from Tom with source listing, but I use Geir's version.

Geir's version includes the following instruction sequence in two places:

FS? 31
XEQ "DMD"
Flag 31 is a system flag that indicates the date format, but I don't seem to have the program "DMD". I suspect that it is Geir's own program for processing the date or its format.

Geir's program fits on three HP-41 magnetic cards (Tom's original fits on two).

-- KS


#22

Right, the DMD...

What it does is just to convert the date formats - between DD.MMYYYY and MM.DDYYYY (either way), like this:

LBL "DMD"
ENTER
INT
X<>Y
FRC
100
*
ENTER
INT
X<>Y
100
/
+
X<>Y
100
/
+
END


Edited: 18 Oct 2010, 7:46 a.m.


#23

 01 LBL "DMD"
02 INT
03 LASTX
04 FRC
05 100
06 *
07 INT
08 X<>Y
09 LASTX
10 FRC
11 +
12 100
13 /
14 +
15 END

Saves a few bytes.

Best regards

Thomas


#24

Excellent.


#25

LASTX is perhaps the least used instruction in my programs. I should get used to it.

#26

Jeff --

You had found one of the threads regarding Tom Sherman's HP-41 celestial locator program, but there was another thread in 2006 in which Tom contributed and Geir posted his improved version of the program:

http://www.hpmuseum.org/cgi-sys/cgiwrap/hpmuseum/archv016.cgi?read=91858#91858

I will copy and paste Geir's version below, together with the "DMD" program he omitted in 2006 (as recently refined by Thomas Klemm), and also including one worthwhile instruction added by me (003 DEG, to ensure that the degree angular mode is set for calculations).

The "DMD" program allows the user to maintain European-style date mode (dd.mmyyyy), which is initiated by running the Time Module command "DMY" (which sets Flag 31). The Nav Pac subroutine "FA" requires that the input date be formatted US-style (mm.ddyyyy), as documented on page 41 of the Nav Pac manual.

As a side note, years outside the range 1900-1999 are displayed on the HP-41 using four digits. The full dates look nicer in European format on the HP-41's 12-character display.

For guidance in usage, please see Geir's description of the features of his program, in the thread of 2006. I'll also note that entry of an arbitrary date and time is of the form <date> ENTER <time>, occupying two stack levels. In the source code listing, "|-" is the unprintable 'append' character shift-K in ALPHA mode.

The complete, improved program:

001 *LBL "SKY"	       051  "LO" 	       	  101  GTO 02	        151  DATE
002 LBL e 052 XROM "DSPLO" 102 LBL a 152 FS? 31
003 DEG 053 "|-?" 103 "VENUS" 153 XEQ "DMD"
004 CF 01 054 PROMPT 104 AVIEW 154 STO 30
005 CF 02 055 XROM "*HR" 105 6 155 TIME
006 SF 00 056 STO 08 106 LBL 06 156 LBL 12
007 CLK24 057 LBL E 107 XEQ 01 157 RCL 54
008 "DT+TM=<NOW>" 058 "S,V O,M *,J ,SA" 108 .017 158 HMS-
009 CF 22 059 PROMPT 109 + 159 FS? 03
010 PROMPT 060 LBL A 110 STO 34 160 1
011 FC? 22 061 "SUN" 111 XROM "*VENUS" 161 FS? 03
012 GTO 10 062 AVIEW 112 GTO 02 162 HMS+
013 STO 55 063 3 113 LBL b 163 HR
014 X<>Y 064 LBL 03 114 "MARS" 164 RTN
015 FS? 31 065 XEQ 01 115 AVIEW 165 LBL 02
016 XEQ "DMD" 066 .012 116 7 166 RCL 44
017 STO 30 067 + 117 LBL 07 167 RCL 45
018 SF 02 068 STO 34 118 XEQ 01 168 +
019 LBL 10 069 XROM "*SUN" 119 .019 169 RCL 08
020 RCL 54 070 GTO 02 120 + 170 -
021 "TZ= " 071 LBL B 121 STO 34 171 RCL 07
022 ARCL X 072 "MOON" 122 XROM "*MARS" 172 RCL 46
023 PROMPT 073 AVIEW 123 GTO 02 173 XROM "*SRT"
024 STO 54 074 4 124 LBL c 174 CF 21
025 "N" 075 LBL 04 125 "JUPITER" 175 BEEP
026 ASTO Y 076 XEQ 01 126 AVIEW 176 FIX 1
027 "SUM.TIME? <" 077 .026 127 8 177 "ALT= "
028 FS? 03 078 + 128 LBL 08 178 ARCL X
029 "|-Y" 079 STO 34 129 XEQ 01 179 AVIEW
030 FC? 03 080 XROM "*MOON" 130 .02 180 PSE
031 "|-N" 081 GTO 02 131 + 181 PSE
032 "|->" 082 LBL C 132 STO 34 182 "AZI= "
033 CF 23 083 "STAR NO= ?" 133 XROM "*JUPIT" 183 ARCL Y
034 AON 084 PROMPT 134 GTO 02 184 AVIEW
035 PROMPT 085 INT 135 LBL d 185 FC? 01
036 AOFF 086 STO 47 136 "SATURN" 186 STOP
037 FC? 23 087 FIX 0 137 AVIEW 187 SF 01
038 GTO 11 088 "STAR " 138 9 188 GTO IND 56
039 ASTO X 089 ARCL 47 139 LBL 09 189 *LBL "DMD"
040 X NE Y? 090 AVIEW 140 XEQ 01 190 INT
041 SF 03 091 5 141 .024 191 LASTX
042 LBL 11 092 LBL 05 142 + 192 FRC
043 RCL 07 093 XEQ 01 143 STO 34 193 100
044 "LAT" 094 .011 144 XROM "*SATUR" 194 *
045 XROM "DSPL" 095 + 145 GTO 02 195 INT
046 "|-?" 096 STO 34 146 LBL 01 196 X<>Y
047 PROMPT 097 RCL 30 147 STO 56 197 LASTX
048 XROM "*HR" 098 XROM "FA" 148 RCL 55 198 FRC
049 STO 07 099 STO 44 149 FS? 02 199 +
050 RCL 08 100 XROM "*STAR" 150 GTO 12 200 100
201 /
202 +
203 END

-- KS

Edited: 3 Nov 2010, 12:22 a.m. after one or more responses were posted


#27

Karl,

Thanks. I expect to receive the Nav module in the next couple of days - it arrived at my surrogate US destination intact on Thursday. I look forward to trying out these programs and am pleased that, with the DMD program, I can maintain European/Canadian date formats.

Best regards,

Jeff Kearns

#28

I have compiled a ROM file with this program and the ASTRO module U/I add-on, also written by Geir. A MOD file will be posted at TOS in a few days, but it'd good to have some testers before that. Do I hear any volunteers?

Cheers,
ÁM

#29

Karl,

Thanks again for the complete improved program! I have been playing around with the Navigation, Time, and X-Functions modules in what is now a spare 41C. I also picked up a used copy of volumes 1 and 2 of the Admiralty Manual of Navigation - an excellent resource for the theory and practical application of celestial navigation and dead reckoning techniques.

As an aside, I remember reading once in a novel (of all places) that the term "dead reckoning" is a morphed or bastardized version of the original abbreviation of deduced reckoning; "ded. reckoning".

I will try out the program soon and report back!

Jeff


#30

Jeff --

Enjoy using the program, which always gives correct results as far as my unmeasured 'eyeball estimation' tells me.

I expect that you've already entered it manually -- I do not have the means of electronic transmission by HP-41, other than the 'electro-physical' method of using magnetic cards.

(So that's where "dead reckoning" came from!)

-- KS

Edited: 6 Nov 2010, 3:51 p.m.


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