10  COM I,Z1,B[10],C$[10],I2,A[37,61],A$[10]
11  IF A$="1" THEN 120
20  I=1
30  GOTO 50
40  CHAIN "$CIRMO",180
50  PRINT "DO YOU HAVE A STUDENT NUMBER FROM 'EARORB'";
60  INPUT B$[I,I]
70  IF B$="Y" THEN 100
80  PRINT '10"'EARCK' WAS DESIGNED TO CHECK AN ANSWER CALCULATED FROM THE"
90  PRINT "COMPUTER PROGRAM 'EARORB'. TRY IT, YOU MIGHT LIKE IT! (GET-$EARORB)"
100  I2=2
110  GOTO 40
120  A=B=120
130  Q=P=I
140  PRINT '10"DID YOU HAVE THE STANDARD OR COMPLEX PROBLEM";
150  INPUT V$[I,I]
160  IF V$="S" THEN 210
170  PRINT '10"OKAY, WHAT WAS THE INITIAL SEPARATION?  --- ";
180  INPUT I[I]
190  P=I-I
200  GOTO 320
210  PRINT '10"OKAY, LET'S CHECK YOUR ANSWER. COMPLETE THE FOLLOWING TABLE"
220  PRINT "OF VALUES."
230  PRINT TAB(18)'10"INITIAL"TAB(36)"FINAL"
240  PRINT "SEPARATION-------";
250  ENTER A,B,I[I]
260  PRINT TAB(35);
270  INPUT I[3]
280  PRINT "ORBITAL SPEED----";
290  ENTER A,B,I[2]
300  PRINT TAB(35);
310  INPUT I[4]
320  R1=INT(I[I]/10^5)
330  IF R1 >= 67 AND R1 <= 100 THEN 360
340  PRINT '10"YOU HAVE BLOWN IT. YOU GAVE THE WRONG VALUES FOR THE SEPARATION."
350  GOTO 210
360  R2=R1*10^5
370  GOTO 430
380  IF B[1]>B[2] THEN 410
390  R2=INT(R2*B[2]/B[I]+.5)
400  GOTO 430
410  R2=INT(R2*B[I]/B[2]+.5)
420  PRINT "Q="Q
430  W[Q]=R2
440  W[Q+I]=SQR(INT((1.67*5.98*10^13)/R2+.5))
450  Q=Q+2
460  IF Q=5 THEN 480
470  GOTO 380
480  IF  NOT P THEN 550
490  FOR N=I TO 4
500  IF .9 <= W[N]/I[N] OR W[N]/I[N] <= 1.1 THEN 540
510  PRINT '10'10"YOU SLY FOX. THOUGHT THAT WOULD TRIP UP THE COMPUTER DIDN'T YOU."
520  PRINT "WELL IT DIDN'T. PLAY IT STRAIGHT."
530  GOTO 210
540  NEXT N
550  PRINT '10"OKAY, LET'S EXAMINE YOUR ANSWER FOR THE WORK NECESSARY TO"
560  PRINT "CHANGE ORBITS."'10
570  PRINT TAB(6)'10"CHANGE IN ENERGY (WORK IN JOULES) = ";
580  INPUT E2
590  E3=-(W[2]^2)/2*(W[I]/W[3]-I)
600  PRINT '10"THE DEVIATION BETWEEN YOUR RESULT AND THAT FROM 'EARCK' IS:"
610  PRINT TAB(12)"YOUR VALUE"'10'13TAB(12)"------------- = "INT(ABS(100*(E3-E2)/E3))"PERCENT"
620  PRINT TAB(12)"'EARCK' VALUE"
630  PRINT '10'10"DOES THIS DEVIATION SEEM REASONABLE";
640  INPUT B$[I,I]
650  IF B$="Y" THEN 700
660  PRINT '10"YOU HAVE APPARENTLY MADE AN ERROR IN YOUR CALCULATION OF THE"
670  PRINT "THE TOTAL ENERGY OF EACH ORBIT. PERHAPS A SECOND LOOK AT"
680  PRINT "AT THE WORKSHEET WOULD CLEAR THE ISSUE."
690  GOTO 720
700  PRINT '10"PERHAPS YOU WOULD LIKE TO EXPAND ON THE THE IDEA OF ELLIPTICAL"
710  PRINT "ORBITS. CHECK THE WORKSHEET FOR ADDITIONAL REFERENCES."
720  END 
