upper drive shaft of the sewing machine makes one complete rotation the timing signal of the pulse generator sg sets the flip flop circuit ff2 and the astable multivibrator circuit am oscillates as the counter c advances a number 1 as shown in fig4 the data d5 at the address n 1 is logic 1 and therefore the astable multivibrator am stops the oscillation then the data 16 at the output dp of the memory rom control the second stitch with further rotation of the upper drive shaft of the sewing machine the data 5 at the addresses n 2 and n 3 are logic 0 and therefore these addresses are passed over when the address n 4 is reached the data d5 is 1 and the data 13 at the output dp controls the third stitch as shown in fig4 the following stitches are controlled by the data of the output dp 18 11 20 9 22 8 24 6 26 4 28 2 30 and 0 with further advance of the addresses the data d3 d2 d1 and the data d3 d2 d1 are not in accord and the addresses m and o are passed over and the address n is reached thus the.