div $t0,$s1,$s2

Translates into:

div   $s1,$s2
mflo  $t0

div and divu Pseudoinstruction

The SPIM extended assembler includes these instructions:

div  d,s,t # divide $s by $t. Put the
           # quotient in $d. Operands are
           # two's complement.
           # (pseudoinstruction)

and

divu d,s,t # divide $s by $t. Put the
           # quotient in $d. Operands are
           # unsigned.
           # (pseudoinstruction)