Viking Mars Lander Game for the HP-65

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The program presented below will allow you to try to land the Viking Mars lander on the HP-65. It was written by Kenneth Hopping and appeared in the V4N6P40 issue of PPC Journal (June 1977). Thanks to Kenneth wherever he is today!

Instructions:
1) Load the program.
2) Start the game by pressing A. See VEL.ALT displayed. (Velocity.Altitude)
3) Burn fuel to control your descent. Enter the amount to burn and press D. Your updated VEL.ALT is displayed.
4) A burn of 5 balances the pull of gravity (you don't speed up or slow down).
5) To see fuel remaining, press C. To go back to VEL.ALT, press B.
6) Continue with steps 3, 4 and 5 until you either land safely or crash. Display will show -NN.N as impact speed. a 0.0000 indicates a perfect landing.
7) If you run out of fuel and don't want to delay the inevitiable, press E to free fall until you crash.


Program Listing: Email if you have any questions.
Line      Instruction  Keycode
01         1            01
02         5            05
03         0            00
04         STO 3        33 03
05         5            05
06         0            00
07         0            00
08         ENTER        41
09         5            05
10         0            00
11         CHS          42
12         GTO          22
13         0            00
14         LBL          23
15         D            14
16         STO 5        33 05
17         g            35
18         ABS          06
19         1            01
20         0            00
21         X <> Y       35 07
22         X > Y        35 24
23         0            00
24         /            81
25         RCL 3        34 03
26         X <> Y       35 07
27         X > Y        35 24
28         0            00
29         /            81
30         -            51
31         STO 3        33 03
32         RCL 5        34 05
33         RCL 4        34 04
34         +            61
35         STO 4        33 04
36         2            02
37         /            81
38         RCL 1        34 01
39         +            61
40         RCL 2        34 02
41         +            61
42         0            00
43         X > Y        35 24
44         GTO          22
45         E            15
46         X <> Y       35 07
47         RCL 4        34 04
48         RCL 1        34 01
49         +            61
50         LBL          23
51         0            00
52         STO 1        33 01
53         f            31
54         INT          83
55         X <> Y       35 07
56         STO 2        33 02
57         EEX          43
58         4            04
59         /            81
60         STO 5        33 05
61         RDN          35 08
62         X > Y        35 24
63         RCL 5        34 05
64         +            61
65         X < = Y      35 22
66         RCL 5        34 05
67         -            51
68         STO 5        33 05
69         5            05
70         CHS          42
71         STO 4        33 04
72         LBL          23
73         B            12
74         RCL 5        34 05
75         DSP          21
76         .            83
77         4            04
78         R/S          84
79         LBL          23
80         E            15
81         RCL 1        34 01
82         f-1          32
83         SQRT         09
84         RCL 2        34 02
85         RCL 4        34 04
86         *            71
87         2            02
88         *            71
89         -            51
90         f            31
91         SQRT         09
92         CHS          42
93         STO 3        33 03
94         LBL          23
95         C            13
96         RCL 3        34 03
97         DSP          21
98         .            83
99         1            01
100        R/S          84

That's it!
Visitors since 8/6/97