For the $\text{TTL}$ circuit shown in the figure is find the current through the collector of transistor $Q_{4}$ when $V_{0}=0.2 \mathrm{~V}$. Assume $V_{C E(\text {sat)}}=0.2 \mathrm{~V}, \beta=100$ and $V_{BE(\text {sat})}=0.7 \mathrm{~V}$. The $\alpha$ of $Q_{1}$ in its inverse active mode is $0.01$.
