MIPS data path for store word? -

based on figure, executing sw instruction cause these values assigned signals labeled in blue:

    regwrite = 0     alusrc = 1     alu operation = 0010     memread = 0     memwrite = 1     memtoreg = x     pcsrc =  

however, little confused inputs used in registers block? can describe overall sw procedure in mips datapath?

the execution of sw follow following steps in diagram:

1. instruction read , decoded pc in instruction memory subcircuit.
2. the register file read $rs , $rt (registers subcircuit)
3. the value of $rs added sign extended immediate (selected alusrc) (alu subcircuit).
4. the added value , $rt passed data memory subcircuit value of $rt written memory.