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10-Line Poker Machine
My first entry for the 2020 10-line BASIC contest is a poker machine simulator written in TurboBASIC XL for the Atari 8-bit computer. At ten 120-character lines, it qualifies for the PUR-120 category. It is based on the common “Jacks Or Better” poker machine, although I changed the payouts to make it more fun and to conserve space.
The game deals a hand of five playing cards. You can choose to “hold” any or all of the cards by pressing 1 though 5, then press any other key to replace the cards that you did not hold. (Held cards are not replaced.) It then calculates whether you’ve won, based on standard poker hands.
Here are the payouts:
royal flush +650 (real game: 1250)
royal straight +500 (not in real game)
straight flush +350 (real game: 250)
4 of a kind +225 (real game: 125)
full house +150 (real game: 30)
flush +150 (real game: 25)
straight +200 (real game: 20)
3 of a kind +150 (real game: 15)
2 pair +50 (real game: 10)
pair of Jacks or better +5 (real game: 10)
With all the logic for calculating poker hands, there wasn’t room for card graphics. I did make a custom character set with just one special character: a “10” for the only two-digit card. I am proud of squeezing in money though. You start with $50 in your wallet, and the game costs $5 per hand. The game remembers your wallet by poking it into unused memory ($600, the top of Page 6) then peeking it back after it re-RUNs. Because RUN clears all the variables, this uses much less program space than resetting all the variables by hand.
Here’s the code:
GR.0:POKE 752,1:REM SET UP SCREEN
DIM D(9),U(53),C(13),W$(29),I$(1),H(5),F$(8),SUIT$(4),N$(13)
F$="\00\CE\DB\DB\DB\DB\CE\00"
B=DPEEK($600)-5:'money. minus 5 builds in the cost of the round.
B=B+(45*(B<0)):'that is, IF(B<0) THEN B=50-5.
'Since there's not enough space to zero-out necessary variables if
'we were to loop to play again, and we lose all variables at re-RUN:
'we save user's money in page 6 where it's safe from BASIC.
'On first run, cross our fingers that $600 is seeded
'at 0, otherwise \_(?)_/
?"$";B:?
REM D - cards in shuffled order. This game only deals max 10 cards
REM U - tracks whether card number in subscript has been shuffled in
REM C - Counts number of each card in suit
REM W$ - Win/loss text
REM I$ - storage for INKEY$
REM H - tracks which of the 5 card slots are Held
REM F$ - custom character ("10")
REM SUIT$ - control characters for suits
REM N$(13) - card name characters (A thru K)
SUIT$="\00\10\60\7B":'heart club diamond spade
N$="A23456789#JQK":'one-character card names. '10' replaces #
'Replace '#' with "10" character
CH=(PEEK(106)-16)*256:MOVE 57344,CH,1024
MOVE ADR(F$),CH+24,8:POKE 756,CH/256
'SHUFFLE
FOR X=0 TO 9:'Fill slots. Only slotting 10 cards is faster than 52.
N=0
WHILE N=0:'while we haven't found a card for this slot
NN=RAND(52):'which card might go in this slot?
IF (U(NN)=0):'if we haven't slotted this card yet
D(X)=NN:'slot now contains this card
U(NN)=1:'mark card as used in a slot
N=1:'move on to next card
ENDIF
WEND
NEXT X
REM FORCE CARDS FOR TESTING
'D(0)=12
'D(1)=12+13
'D(2)=13+6
'D(3)=13+13+6
'D(4)=15
FOR GO=1 TO 2:'Do the next part twice
'SHOW CARDS
FOR X=0 TO 4
'Show card name, suit, and the slot number
N=D(X) MOD 13+1:M=D(X) DIV 13+1:?N$(N,N);SUIT$(M,M);" \1B\7F";X+1
'D(X) MOD 13+1 is the card number 1-13
'D(X) DIV 13+1 is the suit 1-4
'This is very clever.
NEXT X
IF(GO=1):'Choose hold cards, first time though only
WHILE QQ=0
POKE 764,255
WHILE I$=""
I$=INKEY$
WEND
POKE 764,255:I$=""
I=ASC(I$)-49
IF(I>=0 AND I<5)
H(I)=NOT H(I):'Toggle hold status for chosen slot
POS.9,I+2
IF(H(I)):?"HOLD":ELSE:?" ":ENDIF
ELSE
QQ=1
ENDIF
WEND
'Replace cards that were not held. 'Every card has one potential replacement
FOR X=0 TO 4
D(X)=D(X+5*(1-H(X)))
'if held, D(X)=D(X), unchanged. if not, D(X)=D(X)+5
'or, more readably: IF(H(X)=0):D(X)=D(X+5):ENDIF
NEXT X
ENDIF
POS.2,8*GO:'Show new cards under old cards
NEXT GO
'Game is over, now see if it's a wining hand
'Count each card type in the hand
F=(D(0) DIV 13)+1:'F="is there a flush?" seed with 0th card suit
FOR X=0 TO 4
N=D(X) MOD 13
C(N)=C(N)+1:'C(N) is how many of that card in the hand
'T is the maximum number of similar cards we've found
T=T+(C(N)-T)*(C(N)>T)
'or, more readably: IF (C(N)>T):T=C(N):ENDIF
F=((D(X) DIV 13)+1=F)*F:'if suit is not the same, set F to 0. I feel clever.
NEXT X
'Count pairs - how many sets of exactly 2 are in the hand?
FOR X=0 TO 12
P=P+(C(X)=2)
'Or, IF (C(X)=2):P=P+1:ENDIF
NEXT X
'FULL HOUSE OR 3 OF A KIND OR 4 OF A KIND
IF T>2:'really this is: IF T=3 OR T=4 becasue it can't be more
IF P:'If there's also a pair
W$="FULL HOUSE"
B=B+150
ELSE
W$=STR$(T)
W$(2)=" OF A KIND":'msg is 3 or 4 of a kind
B=B+(T-1)*75
ENDIF
ELSE:'max same cards T <= 2
IF ((C(10)=2) OR (C(11)=2) OR (C(12)=2) OR (C(0)=2))
W$="JACKS OR BETTER"
B=B+5
ENDIF
IF(P=2)
W$="2 PAIR"
B=B+50
ENDIF
ENDIF
C(13)=C(0):'Kludge to copy Ace to above King
FOR X=0 TO 9
IF (C(X) AND C(X+1) AND C(X+2) AND C(X+3) AND C(X+4))
W$="STRAIGHT "
B=B+200
IF (X=9)
W$="ROYAL "
B=B+250
ENDIF
ENDIF
NEXT X
'Print win/loss message
IF(W$="" AND F=0)
?"LOSE";
ELSE
?W$;
IF F
?"FLUSH";
B=B+150
ENDIF
ENDIF
?:?"$";B
DPOKE $600,B
'Save $ on page 6 for next round
'WAIT FOR KEYPRESS, PLAY AGAIN
WHILE INKEY$="":WEND
RUN