Computer Science 161

Professor Valente

An Example of early FORTRAN progamming

The Algorithm:

Set the value of Sum to 0

Get a value for X

While X is not 0

Set the value of Sum to Sum + X

Get a value for X

End While

Print the value of Sum

Stop

Our VSC-32 assembly language program to solve this problem:

LOAD Zero

STORE Sum

READ X

While: LOAD X

JUMP Print

LOAD Sum

ADD X

STORE Sum

READ X

LOAD Zero

JUMP While

Print: WRITE Sum

STOP

Zero: DATA 0

Sum: DATA 0

X: DATA 0

An Early FORTRAN program to solve this problem:

INTEGER SUM

INTEGER X

SUM = 0

10 READ (1, 5) X

5 FORMAT (I2)

IF (X .EQ. 0) GO TO 30

SUM = SUM + X

GO TO 10

30 WRITE (2, 25) SUM

25 FORMAT (I3)

END