Questions

The First Generation Computers size was very large. 

Since the First generation computers used 1000s of vacuum tubes that required lot of space made them gigantic in size. Single transistor could replace 1000 vacuum tubes and a single IC chip replaced 1000s of transistors made computers smaller and more speedy.

It is obvious that computers developed with more power, reliability, speed and smaller sizes due to the enhancement of technology.

ATX (Advanced Technology extended) is a motherboard form factor uses one 20 pin connector.

ATX is developed by Intel in 1995 to improve on previous de facto standards like the AT form factor. It was the first major change in desktop computer enclosure, motherboard, and power supply design in many years, improving standardization and interchangeability of parts.