Identify the circuit below.

For the circuit shown in the figure, the delays of NOR gates, multiplexers and inverters are 2 ns, 1.5 ns and 1 ns, respectively. If all the inputs P, Q, R, S and T are applied at the same time instant, the maximum propagation delay (in ns) of the circuit is ___________.

A 1-to-8 demultiplexer with data input D$$_{in}$$ , address inputs S$$_{0}$$, S$$_{1}$$, S$$_{2}$$ (with S$$_{0}$$ as the LSB) and $${\overline Y _0}$$ to $${\overline Y _7}$$ as the eight demultiplexed outputs, is to be designed using two 2-to-4 decoders (with enable input $$\overline E $$ and address inputs A$$_{0}$$ and A$$_{1}$$) as shown in the figure. $${D_{in}}$$, S$$_{0}$$, S$$_{1}$$and S$$_{2}$$ are to be connected to P, Q, R and S, but not necessarily in this order. The respective input connections to P, Q, R, and S terminals should be

An 8-to-1 multiplexer is used to implement a logical function Y as shown in the figure. The output Y is given by