Ask HN: Non-restoring division algorithm doubt?

This is the algorithm for non-restoring division:

https://imgur.com/zJF0Ky9

The book does provides an example with dividend=1100001 and divisor=1010

But it represents it weirdly. Nowhere has been mentioned about that.

https://imgur.com/GuWv3wW

The dividend is placed by left shifting it by 1 bit. Why is it that case? The author has not mentioned to start putting the divisor starting from S(sign) register. It is automatically been initialized to 0.

Please help a bit.