1 REM BRAIN SIMULATOR PROGRAM
2 REM *** REVISED BY EDWARD BAKER AND RON REISOR **********************
5 GOTO 1020:DIMD(256):MATD=ZER
7 D2=A
9 PRINT 'MEMORY HAS BEEN CLEARED'
1010 DIM R(16),M(256)
1020 H$='0123456789ABCDEF'
1100 PRINT
1101 PRINT"TYPE 'LOAD' OR 'START' OR 'STOP'"
1110 INPUT I$
1120 IF I$='LOAD' THEN 2110
1130 IF I$='START' THEN 3010
1140 IF I$<>'STOP' THEN 1100
1160 PRINT'DONE':GOTO9990
2000 REM   ***   LOAD   ***
2110 PRINT
2120 GOSUB 9800
2140 PRINT'ADDRESS INSTRUCTIONS/DATA COMMENTS'
2210 N=A
2220 GOSUB 9100
2225 PRINT MID(A$,3,4);'      ';
2230 INPUT I$
2240 A1=A
2250 IF MID(I$,1,3)='SEE' THEN 2810
2260 IF MID(I$,1,3)='SET' THEN 2910
2270 IF MID(I$,1,3)='END' THEN 2960
2310 FOR L=1 TO LEN(I$)
2320 T5$=MID(I$,L,1):IFT5$=' 'ORT5$=CHR$(9%)THEN2440
2330 NEXT L
2335 GOTO 2450
2440 L=L-1
2450 IF L/4=INT(L/4) THEN 2610
2460 PRINT'NUMBER OF DIGITS IS NOT A MULTIPLE OF FOUR'
2510 PRINT'PLEASE RETYPE INSTRUCTION'
2520 A=A1
2530 GOTO 2210
2610 FOR I=1 TO L STEP 4
2620 A$=MID(I$,I,4)
2630 GOSUB 9200
2640 IF M>1.E+08 THEN 2710
2650 M(A+1)=N
2660 A=A+1
2670 IF A<256 THEN 2680
2675 A=0
2680 NEXT I
2690 GOTO 2210
2710 PRINT'ILLEGAL CHARACTER IN INSTRUCTION ';A$
2720 GOTO 2510
2810 GOSUB9400
2820 IFN>255THEN2510
2830 A=N
2840 I$=MID(I$,5,2)
2845 I$=LEFT(I$,2)+SPACE$(6)+RIGHT(I$,9)
2850 M7=7
2851 IF A<249 THEN 2860
2852 M7=255-A
2860 FOR I=0 TO M7
2861 I5=I*5
2862 I$=LEFT(I$,8+I5)+' '+RIGHT(I$,10+I5)
2863 N=M(A+1+I)
2864 GOSUB 9100
2865 I$=LEFT(I$,9+I5)+A$+RIGHT(I$,14+I5)
2866 NEXT I
2870 PRINT I$
2880 GOTO 2210
2910 GOSUB 9400
2920 IF N>255 THEN 2510
2930 A=N
2940 GOTO 2210
2960 GOSUB 9400
2970 IF N>255 THEN 2510
2980 A=N
2990 GOSUB 9900
2995 GOTO 1100
3000 REM ***   START   ***
3010 PRINT
3012 GOSUB 9800
3016 N=A
3017 GOSUB 9100
3018 PRINT'EXECUTION BEGINS WITH INSTRUCTION AT ADDRESS ';MID(A$,3,2)
3019 PRINT
3020 MAT R=ZER
3025 T=0
3029 FOR Q=1 TO 10000
3030 R0=INT(M(A+1)/256)
3040 REM   E IS THE ADDRESS PORTION OF THE INSTRUCTION
3041 E=M(A+1)-256*R0
3050 REM   C IS THE OPERATION CODE
3051 C=INT(R0/16)
3060 REM   R0 IS THE REGISTER NUMBER IN THE INSTRUCTION
3061 R0=R0-16*C
3070 IF C>=0 THEN 3090
3080 C=C+16
3090 IF C>7 THEN 3095
3091 ON C+1 GOTO 4000,4100,4200,4300,4400,4500,4600,4700
3095  ON C-7 GOTO 4800,4900,5000,5100,5200,5300,5400,5500
4000 REM   ***   OUTPUT
4010 PRINT ' ';M(E+1)
4020 GOTO 6210
4100 REM   ***   INPUT
4110 INPUT N
4120 REM IF N=INT(N) AND N>=-32768 AND N<=32767 THEN 4160
4121 IF N-INT(N)+SGN(32767.6-ABS(N+.5))=1 THEN 4160
4130 PRINT'INPUT MUST BE AN INTEGER BETWEEN -32768 AND 32767'
4140 PRINT'PLEASE RETYPE INPUT'
4150 GOTO 4110
4160 M(E+1)=N
4170 GOTO 6210
4200 REM   ***   SUBTRACT
4210 R1=INT(E/16)
4220 T=R(R1+1)-R(E-R1*16+1)
4230 GOTO 6110
4300 REM   ***   LOAD
4310 R(R0+1)=M(E+1)
4320 GOTO 6210
4400 REM   ***   UNLOAD (STORE9
4410 M(E+1)=R(R0+1)
4420 GOTO 6210
4500 REM   ***   MULTIPLY
4510 R1=INT(E/16)
4520 T=R(R1+1)*R(E-R1*16+1)
4530 GOTO 6110
4600 REM   ***   OP-CODE 6 NOT USED
4700 REM   ***   OP-CODE 7 NOT USED
4800 REM   ***   OP-CODE 8 NOT USED
4900 REM   ***   OP-CODE 9 NOT USED
4901 N=A
4902 GOSUB 9100
4903 PRINT'ILLEGAL OP-CODE IN INSTRUCTION AT ADDRESS ';MID(A$,3,2)
4904 GOTO 8110
5000 REM   ***   ADD
5010 R1=INT(E/16)
5020 T=R(R1+1)+R(E-R1*16+1)
5030 GOTO 6110
5100 REM   *** BRANCH
5110 N=INT(R0/2^(SGN(T)+1))
5120 REM   IF N IS EVEN AND R0<7 THEN 6210
5121 IF N/2-INT(N/2)+SGN(7-R0)=1 THEN 6210
5130 A=E
5140 GOTO 6220
5200 REM   ***   COUNT
5210 N=R(R0+1)
5220 IF N=-32768. THEN 6140
5230 R(R0+1)=N-1
5240 IF N=1 THEN 6210
5250 A=E
5260 GOTO 6220
5300 REM   ***   DIVIDE
5310 R1=INT(E/16)
5320 N=R(E-R1*16+1)
5330 IF N=0 THEN 5360
5340 T=INT(R(R1+1)/N)
5350 GOTO 6110
5360 N=A
5370 GOSUB 9100
5380 PRINT'ATTEMPT TO DIVIDE BY ZERO AT ADDRESS ';MID(A$,3,2)
5390 GOTO 8110
5400 REM  *** ENTER
5410 IF E<128 THEN 5430
5420 E=E-256
5430 R(R0+1)=E
5440 GOTO 6210
5500 REM   ***   HALT
5510 PRINT
5520 N=A
5530 GOSUB 9100
5540 PRINT'HALT INSTRUCTION AT ADDRESS ';MID(A$,3,2);' EXECUTED'
5550 GOTO 1100
6100 REM   *** CHECK FOR OVERFLOW
6110 REM  IF T>-32768 AND T<32767 THEN 6160
6111 IF ABS(T+.5)<32767.6 THEN 6160
6120 N=A
6130 GOSUB 9100
6140 PRINT'OVERFLOW RESULTED FROM INSTRUCTION AT ADDRESS ';MID(A$,3,2)
6150 GOTO 8110
6160 R(R0+1)=T
6210 A=A+1
6211 IF A<256 THEN 6220
6212 A=0
6220 NEXT Q
6230 PRINT'10000 INSTRUCTIONS HAV BEEN EXECUTED'
8100 REM   ***   MEMORY DUMP
8110 PRINT
8120 PRINT'CONTENTS OF REGISTERS'
8130 PRINT'REG   HEX   DECIMAL         REG   HEX   DECIMAL'
8140 FOR I=1 TO 8
8150 REM   IF R(I)=0 AND R(I+8)=0 THEN 8220
8151 IF ABS(R(I))+ABS(R(I+8))=0 THEN 8220
8160 N=R(I)
8170 GOSUB 9100
8180 I$=A$
8190 N=R(I+8)
8200 GOSUB 9100
8210 PRINTI-1;'   ';I$;'  ';R(I);'          ';I+7;'  ';A$;'  ';R(I+8)
8220 NEXT I
8230 PRINT
8240 PRINT'CONTENTS OF MEMORY IN HEXADECIMAL'
8250 FOR A=0 TO 255 STEP 8
8260 FOR J=A+1 TO A+8
8270 IF M(J)<>0 THEN 8300
8280 NEXT J
8290 GOTO 8410
8300 N=A
8310 GOSUB 9100
8320 I$=MID(A$,3,2)
8330 I$=LEFT(I$,2)+SPACE$(6)+RIGHT(I$,9)
8340 FOR K=0 TO 7
8350 J5=K*5
8360 N=M(A+K+1)
8370 GOSUB 9100
8380 I$=LEFT(I$,8+J5)+' '+RIGHT(I$,10+J5)
8390 I$=LEFT(I$,9+J5)+A$+RIGHT(I$,14+J5)
8395 NEXT K
8400 PRINT I$
8410 NEXT A
8420 GOTO 1100
9100 REM   ***   CONVERTS N INTO 4 HEX DIGITS A$   ***
9101 A$='    '
9110 FOR J=4 TO 2 STEP -1
9111 N1=INT(N/16)
9112 H=N-N1*16+1
9113 N=N1
9114 A$=LEFT(A$,J-1)+MID(H$,H,1)+RIGHT(A$,J+1)
9115 NEXT J
9120 IF N>=0 THEN 9140
9130 N=N+16
9140 A$=MID(H$,N+1,1)+RIGHT(A$,2)
9150 RETURN
9200 REM  ***   CONVERTS 4 HEX DIGITS A$ INTO N   ***
9210 C$=MID(A$,1,1)
9220 GOSUB 9300
9230 IF H<0 THEN 9280
9240 IF H<8 THEN 9260
9250 H=H-16
9260 N=H
9270 FOR J=2 TO 4
9271 C$=MID(A$,J,1)
9272 GOSUB 9300
9273 IF H<0 THEN 9280
9274 N=N*16+H
9275 NEXT  J
9276 RETURN
9280 N=1.E+09
9290 RETURN
9300 REM   ***   CONVERTS CHARACTER C$ INTO HEX DIGIT H  ***
9310 FOR H=1 TO 16
9320 IF MID(H$,H,1)=C$ THEN 9350
9330 NEXT H
9340 H=0
9350 H=H-1
9360 RETURN
9400 REM   ***   SETS N TO NEW ADDRESS BY MID(I$,4,6)
9410 IF LEN(I$)=3 THEN 9450
9420 IF MID(I$,4,1)=' ' THEN 9450
9430 IF LEN(I$)<6 THEN 9440
9431 IF MID(I$,4,1)='-' THEN 9460
9440 N=999
9441 GOTO9480
9450 I$=LEFT(I$,3)+'-00'+RIGHT(I$,7)
9460 N=0
9461 A$='00'+RIGHT(A$,3)
9462 A$=LEFT(A$,2)+MID(I$,5,2)+RIGHT(A$,5)
9463 GOSUB 9270
9470 IF N<256 THEN 9490
9480 PRINT'AFTER THE THREE LETTER COMMAND SHOULD BE'
9481 PRINT'      EITHER NOTHING OF ELSE "-HH" WHERE'
9482 PRINT'      EACH H IS A HEXADECIMAL DIGIT'
9490 RETURN
9800 REM   ***   FETCH VALUES OF M AND A
9810 MAT M=D
9820 A=D2
9830 RETURN
9900 REM   ***   SAVE M AND A
9910 MAT D=M
9920 D2=A
9930 RETURN
9990 END