DAVIAC2 has a BASIC interpreter!

After much hard work, the DAVIAC2 now has a BASIC interpreter, here's a sample:

  RUN
  A,B,C,D
  -1,9,2,0
                                                                              *
                                                                  *
                                                         *
                                                  *
                                             *
                                          *
                                        *
                                        *
                                        *
                                         *
                                           *
                                            *
                                             *
                                              *
                                             *
                                            *
                                        *
                                    *
                             *
                    *
        *
 END
 LIST

 10 INPUT "A,B,C,D" A,B,C,D
 11 REM
 20 LET X=-20
 21 REM
 30 LET I=X*X,J=B*I
 31 LET K=I*X,L=A*K
 32 LET M=C*X
 33 LET N=L+J,N=N+M,O=N+D
 34 LET O=O/20
 35 REM
 40 LET P=O+40
 41 IF P<0 GOTO 80
 42 IF P>79 GOTO 80
 43 REM
 50 LET I=0
 51 IF I=P GOTO 60
 52 PRINT " ":
 53 LET I=I+1
 54 GOTO 51
 55 REM
 60 PRINT "*"
 61 GOTO 90
 70 REM
 80 PRINT ""
 81 REM
 90 LET X=X+1
 91 IF X<21 GOTO 30
 99 END
 
 28 Lines of 32
 333 Bytes used of 512 available````