Why is one of the transistors in ROM sense amplifier twice the width of the one opposite of him?
the one on the right sees two signals a "0" (\$I_0\$) 
and a "1" (\$I_1\$)
the one on the left sees one signal \$I_m\$ a '0' or a 'i'

the compartor computes \$ I_m &gt; ( I_0 + I_1 ) / 2 \$

To get the /2 it needs to be twice as wide on other side