1.　　Access the relevant reference books or technical data books and give accurate definitions for the following timing parameters:

(1) propagation time tPD,

(2) transition time tTD,

(3) setup time tSU,

(4) hold time tHD, and

(5) clock-to-output time tCO.

2.　　Compare the main features of 74-393 and 74-163 counters and construct an N-bit synchronous counter using 74-163(s).

3.　　Macrocells (MCs) are key components of Programmable Logic Device (PLD). Based on the MC logic schematic diagram below, please describe its functions.