c Simple Conway's game of life
c FORTRAN77 version 
c use the makefile to build 
c jrs 10.21.2002
      parameter (N=80)
      dimension cell(80,80), cell0(80,80)
      real x,y,xb,yb,q

c initialize using built-in random number function

      do 200 I=1, N
         do 100 J=1, N
            if(rand().gt.0.5) then
               cell0(I,J)=1
               else
                  cell0(I,J)=0
                  end if
 100              continue
 200              continue

c set up a graphics device

      dev=g2_open_vd() 
      write (6,*) dev    
      dev1=g2_open_X11(400.0, 400.0)
      write (6,*) dev1
      call g2_attach(dev, dev1)

c evolution step first loop is time loop

      do 900 IT=0, 100

c set up correct boundary conditions (that means YOU)
c I will update the interior cells...

      do 400 I=2, N-1
         do 300 J=2, N-1
            IS=cell0(I-1,J+1)+cell0(I, J+1)+cell0(I+1, J+1)
            IS=IS+cell0(I-1,J)+cell(I+1,J)
            IS=IS+cell0(I-1,J-1)+cell0(I, J-1)+cell0(I+1, J-1)
            if((cell0(I,J).eq.0).and.(IS.eq.3)) then
               cell(I,J)=1
            else if ((cell0(I,J).eq.1).and.((IS.eq.2).or.(IS.eq.3)))then
               cell(I,J)=1
            else
               cell(I,J)=0
            end if
 300        continue
 400        continue

c then for example... top
            do 1000 J=2, N-1
               IS=cell0(J-1,N-1)+cell0(J,N-1)+cell0(J+1,N-1)
               IS=IS+cell0(J-1,N)+cell0(J+1,N)
               if((cell0(J,N).eq.0).and.(IS.eq.3)) then
               cell(J,N)=1
            else if ((cell0(J,N).eq.1).and.((IS.eq.2).or.(IS.eq.3)))then
               cell(J,N)=1
            else
               cell(J,N)=0
            end if
 1000       continue


c ... the left wall
            do 2000 J=2, N-1
               IS=cell0(2,J-1)+cell0(2, J)+cell0(2, J+1)
               IS=IS+cell0(1,J-1)+cell0(1, J+1)
               if((cell0(1,J).eq.0).and.(IS.eq.3)) then
               cell(1,J)=1
            else if ((cell0(1,J).eq.1).and.((IS.eq.2).or.(IS.eq.3)))then
               cell(1,J)=1
            else
               cell(1,J)=0
            end if
 2000       continue

c right wall
            do 3000 J=2, N-1
               IS=cell0(N-1,J-1)+cell0(N-1, J)+cell0(N-1, J+1)
               IS=IS+cell0(N,J-1)+cell0(N, J+1)
               if((cell0(N,J).eq.0).and.(IS.eq.3)) then
               cell(N,J)=1
            else if ((cell0(N,J).eq.1).and.((IS.eq.2).or.(IS.eq.3)))then
               cell(N,J)=1
            else
               cell(N,J)=0
            end if
 3000       continue

c then for example... top
            do 4000 J=2, N-1
               IS=cell0(J-1,2)+cell0(J,2)+cell0(J+1,2)
               IS=IS+cell0(J-1,1)+cell0(J+1,1)
               if((cell0(J,1).eq.0).and.(IS.eq.3)) then
               cell(J,1)=1
            else if ((cell0(J,1).eq.1).and.((IS.eq.2).or.(IS.eq.3)))then
               cell(J,1)=1
            else
               cell(J,1)=0
            end if
 4000       continue
c we SHOULD update the four corners, bugger the corners!          
c drawing portion
 
      do 600 I=1, N
         do 500 J=1, N
           
                  x=5.0*float(I)-5.0
                  y=5.0*float(J)-5.0
                  xb=x+5.0
                  yb=y+5.0
                  call g2_pen(dev1, cell(I,J))
                  call g2_filled_rectangle(dev1, x,y,xb,yb)
                  
 500              continue
 600              continue

c resetting portion
                  
      do 800 I=1, N
         do 700 J=1, N
            cell0(I,J)=cell(I,J)
 700        continue
 800        continue

 900        continue

c time loop ends, now wait for key input
            read (*,*) q
            call g2_close(dev)
            stop
      end