The Museum of HP Calculators

Scatter for the HP-41C/CV/CX

This program is Copyright © HP and is used here by permission. It was originally printed in the Games Solution Book. This program was entered and uploaded by Tony Duell. The documentation was entered by Dave Hicks. The Barcode for this program was provided by Brian Ward.

This program is supplied without representation or warranty of any kind. Tony Duell, Hewlett Packard 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

N atoms are randomly placed in a black box with dimensions l0x10. No atom can be on the edge of the box. By firing particles into the box from the edges, and noting their exit locations, you attempt to find the atom positions. For a single atom, the scatters and reflections are as shown in Figure 1. Multiple atom scatters are simple extensions of this diagram: See, for examples, Figures 2 and 3. Note in particular, the back reflections of Figure 3 which arise from two combined scatters. More complex scattering and reflection are shown in Figure 4 where atom 4 causes scatter A, atom 2 causes B, 1 causes C, 4 (again) causes D, 3 causes E, and atom 1 reflects the particle back along the convoluted path. The numbering of the box grid is given in Figure 5. The 5th position on the base has coordinates 5.0, the 7th on the right is 9.7, and so on.

You select the value of N, and the machine places the N atoms randomly. You then fire particles from the edge: The machine tracks them and displays the output edge locations. At any time you can get the machine to confirm or reject any suspected atom location. If the guess is wrong, you are "penalized" by having the number of used particles increased by 5. The object of the game is not only to find the atoms, but to do so with the minimum number of probes.

NOTE: Although 9 atoms may be placed, a "good" game is 4 or 5.

Diagrams

Note: Requires 1 Memory Module on HP-41C

Instructions

 Step Instructions Input Data/Units Keys Output Data/Units 1 Enter program 2 Initialize [XEQ] SCATTER SEED? 3 Key in number between 0 and 1 seed [R/S] NO. OF ATOMS? 4 Key in number of atoms to be placed. N [R/S] READY 5 Key in an entrance point. x.y [R/S] (x).(y) 6 To guess a position key one in. x.y [A] YES (or) NO ( ) PROBES Continue with steps 5 and 6 as desired. 7 To start a new game go to step 4. [E] NO. OF ATOMS? 8 If at any time you give up you can find all positions. [C] (x).(y) . . .

Example

Set up and find 4 atoms

```   Keystrokes:          Display:
[XEQ] [ALPHA]
SIZE [ALPHA] 022
[XEQ] [ALPHA]
SCATTER [ALPHA]         SEED?
.191062 [R/S]           NO. OF ATOMS?
2.0 [R/S]               0,2
4.0 [R/S]               9,2
3.3 [A]                 YES
2 PROBES
6.9 [R/S]               6,9
6.8 [A]                 NO
8 PROBES
0.8 [R/S]               9,8
.                        .
.                        .
```

How to get this Program to your Calculator (via HP-IL, disk, wand, and fingers)
Display the Program Barcode (.pdf) for printing and scanning

Program Listing

```LINE  KEYS
01 LBL "SCATTER"
02 SF 27
03 CF 29
04 SF 28
05 FIX 00
06 "SEED?"
07 PROMPT
08 STO 00
09 LBL E
10 0
11 STO 11
12 "NO. OF ATOMS?"
13 PROMPT
14 STO 10
15 1 E3
16 /
17 1
18 +
19 STO 12
20 LBL 00
21 XEQ 10
22 XEQ 10
23 10
24 /
25 +
26 RCL 12
27 INT
28 X<>Y
29 STO 09
30 LBL 01
31 RCL IND Y
32 X=Y?
33 GTO 00
34 RDN
35 LBL 09
36 DSE Y
37 GTO 01
38 STO IND 12
39 ISG 12
40 GTO 00
42 AVIEW
43 GTO 20
44 LBL 10
45 RCL 00
46 9821
47 *
48 .211327
49 +
50 FRC
51 STO 00
52 8
53 *
54 1
55 +
56 INT
57 RTN
58 LBL 20
59 STOP
60 INT
61 STO 12
62 STO 15
63 CF 00
64 X=0?
65 SF 00
66 9
67 X=Y?
68 SF 00
69 CF 01
70 X=Y?
71 SF 01
72 LASTX
73 FRC
74 10
75 *
76 STO 13
77 STO 14
78 X=Y?
79 SF 01
80 1
81 ST+ 11
82 LBL 02
83 RCL 10
84 STO 21
85 10
86 STO 17
87 LBL 05
88 RCL IND 21
89 INT
90 LASTX
91 FRC
92 10
93 *
94 RCL 13
95 -
96 X<>Y
97 RCL 12
98 -
99 FS? 00
100 X<>Y
101 STO 20
102 ABS
103 1
104 -
105 X>0?
106 GTO 09
107 RDN
108 STO 16
109 FS? 01
110 CHS
111 X<0?
112 GTO 09
113 RCL 17
114 X<>Y
115 X>Y?
116 GTO 09
117 SF 03
118 X#Y?
119 CF 03
120 STO 17
121 RCL 20
122 STO 18
123 RCL 16
124 STO 19
125 SF 02
126 LBL 09
127 DSE 21
128 GTO 05
129 FS?C 02
130 GTO 09
131 0
132 ENTER
133 9
134 FS? 01
135 X<>Y
136 RCL 12
137 RCL 13
138 FS? 00
139 X<>Y
140 RDN
141 FS? 00
142 X<>Y
143 STO 15
144 RDN
145 STO 14
146 LBL 03
147 CLA
148 ARCL 15
149 ","
150 ARCL 14
151 AVIEW
152 GTO 20
153 LBL 09
154 FS?C 03
155 GTO 03
156 RCL 12
157 RCL 13
158 FS? 00
159 X<>Y
160 RCL 19
161 1
162 FS? 01
163 CHS
164 -
165 +
166 FS? 00
167 X<>Y
168 STO 13
169 RDN
170 STO 12
171 FS? 00
172 SF 02
173 SF 00
174 FS?C 02
175 CF 00
176 CF 01
177 RCL 18
178 X=0?
179 GTO 03
180 X>0?
181 SF 01
182 GTO 02
183 LBL A
184 RCL 10
185 X<>Y
186 LBL 04
187 RCL IND Y
188 "YES"
189 X=Y?
190 GTO 09
191 RDN
192 DSE Y
193 GTO 04
194 5
195 ST+ 11
196 "NO"
197 LBL 09
198 AVIEW
199 PSE
200 CLA
201 ARCL 11
202 " PROBES"
203 AVIEW
204 GTO 20
205 LBL C
206 RCL 10
207 FIX 01
208 CF 28
209 LBL 06
210 CLA
211 ARCL IND X
212 AVIEW
213 PSE
214 DSE X
215 GTO 06
216 SF 28
217 FIX 00
218 GTO 20
219 END
```