11. Indirect addressing was almost as good as index registers . 12. In addition, index registers consist of a lower offset portion and an upper increment portion. 13. The processor may scale the index register to allow for the size of each array element. 14. It is also more efficient to set the index registers to 16 bits before pushing them. 15. Some instructions also subtracted the " decrement " field from the contents of the index registers . 16. The successor of the 701 was the index register -equipped IBM 704, introduced 4 years after the 701. 17. For example, the aforementioned 6502's index registers 'size is 8 bits and the page size is 256 bytes. 18. Standard instructions had a 6-bit operation code, a two-bit index register identifier, and an 8-bit PC-relative address. 19. Index registers are used by instructions to modify the offset of the specified or assumed base register.20. Perhaps the Manchester Mark 1's most significant innovation was its incorporation of index registers , commonplace on modern computers.
