Snakes and Ladders for the HP-41

Overview
 

-You and the HP-41 are on square#0

-The 2 players alternately roll 2 dice. ( Flag F01 is set if it's your turn to play )
-If the dice are D1 D2, the player on square S moves forward on square S+D1+D2

-The snakes and the ladders may appear at random on every square#S provided  1 < S < 100
-When a snake appears, you move back. If a ladder appears, you move forward.

-Ladders are long near square#1, short near square#99
-Snakes are short near square#1,  long near square#99

-The winner is the first one who reaches ( or exceeds ) square#100
 

Program Listing
 

Data Registers:           •  R00 = r = random numbers                          ( Register R00 is to be initialized before executing "SNLD" )

                                         R01 thru R05:  temp

Flags:    F01   when F01 is set, it's your turn to play:  press any key to roll the dice
               F29   when F01 is clear, the HP-41 is playing.
Subroutines: /

-The append character is denoted  ~
-Line 92 is a three-byte  GTO 02
 
 

01  LBL "SNLD"     02  " 00/00"   03  AVIEW   04  CLX   05  STO 01   06  STO 02   07  FIX 0   08  CF 01   09  CF 29   10  XEQ 06   11  4   12  X>Y?   13  SF 01   14  LBL 01   15  FS? 01   16  GETKEY   17  XEQ 06   18  STO 03   19  XEQ 06   20  STO 04   21  +   22  LBL 02   23  FS? 01

24  ST+ 01   25  FC? 01   26  ST+ 02   27  COS   28  COS   29  COS   30  RCL 01   31  10   32  " "       33  X>Y?   34  "~0"     35  ARCL 01           36  "~/"            37  RCL 02   38  X<Y?   39  "~0"      40  ARCL 02   41  "~  "         42  ARCL 03   43  "~+"        44  ARCL 04   45  AVIEW   46  FS? 01

47  RCL 01   48  STO 05   49  99   50  X<Y?   51  GTO 07   52  SIGN   53  X=Y?   54  GTO 03   55  RCL 00   56  R-D   57  FRC   58  STO 00              59  .8       60  X<Y?   61  GTO 04   62  6   63  /      64  X>Y?   65  GTO 05   66  LBL 03   67  FC?C 01   68  SF 01   69  GTO 01

70  LBL 04   71  RCL 05   72  3   73  /   74  1   75  +   76  INT   77  CHS   78  " SNAKE"          79  AVIEW   80  GTO 02   81  LBL 05   82  15   83  RCL 05   84  7   85  /   86  -   87  INT   88  1   89  +   90  " LADDER"   91  AVIEW   92  GTO 02

93  LBL 06   94  RCL 00   95  R-D   96  FRC   97  STO 00   98  6   99  * 100  1 101  + 102  INT 103  RTN 104  LBL 07 105  FS? 01 106  " YOU WIN" 107  FC?C 01 108  " HP-41 WINS" 109  FIX 4 110  SF 29 111  AVIEW 112  END

 
( 210 bytes / SIZE 006 )
 
 

STACK	INPUTS	OUTPUTS
X	/	/

 
Example:        5  STO 00   XEQ "SNLD"

     " 00/00"                  and flag F01 is set: it's your turn to play, press any key
     " 04/00   3+1"         the dice are 3 & 1 so you move on square#04. Flag F01 is cleared so the HP-41 roll the dice
     " 04/07   6+1"         the dice are 6 & 1 the HP-41 move on square#07...
     " SNAKE"              but there is a snake, the calculator moves back...
     " 04/04   6+1"         ... on square#04...
     " LADDER"            a ladder! HP-41 moves forward
     " 04/19  6+1"          ... on square#19 and flag F01 is set again: you press a key
     " 13/19  3+6"          the dice are 3 & 6 so you move on square#13 ... and so forth ...

Notes:

-The HP-41 displays  " S1/S2  D1+D2"    where  S1 is your square,  S2 is HP-41's square,  D1+D2 are the 2 dice.

-Actually, the game is completely determined by the seed you've stored in register R00
-If you want to influence the chance, add  FS? 01  ST+ 00  after line 16:
  the keys you'll press will modify the random numbers in register R00.

-Do not store a number like PI in R00: the sequence of "random" numbers would be 0 0 0 0  ....
 ( or change the random number generator lines 94 to 97 )

-There is a snake if  r > 0.8      where  r is the content of register R00
-There is a ladder if r < 0.8/6
-Change lines 59-62-63  if you prefer more ( or less ) snakes and/or ladders.