Day 2: Pre-Class Self-Check Quiz

Combinational Building Blocks

Q1: Does reg always synthesize to a register?

Answer

No. reg in always @(*) = combinational logic. reg in always @(posedge clk) = flip-flop. The keyword only means "can be assigned in a procedural block."

Q2: What is 4'hF in binary? How many bits?

Answer

4-bit binary 1111 (decimal 15). The 4' specifies 4 bits, h means hexadecimal.

Q3: What does assign y = sel ? a : b; synthesize to?

Answer

A 2-to-1 multiplexer. When sel=1, output is a. When sel=0, output is b.

Q4: What's the difference between & and &&?

Answer

& is bitwise AND (per-bit, result same width). && is logical AND (1-bit true/false result). 4'b1010 & 4'b0101 = 4'b0000 but 4'b1010 && 4'b0101 = 1'b1.