Discuss the bit pattern of the accumulator for SIM instruction?

There are seven bits (one unused) in the accumulator prior to executing the SIM instruction that are of value. Numbering is 7 through 0, where 7 is the most significant...

7-Serial Out data - This sets the SOD pin

6-Enable serial data - if 0, ignore bit 7

5-Unused

4-Reset RST 7.5 flip-flop

3-Mask set enable - if 0, ignore bits 0, 1, and 2

2-Mask 7.5 - if 0, enable RST 7.5

1-Mask 6.5 - if 0, enable RST 6.5

0-Mask 5.5 - if 0, enable RST 5.5