Data exchange - the motherboard

The ROM chips contain instructions, which are specific for that particular motherboard. Those programs and instructions will remain in the PC throughout its life; usually they are not altered.

Primarily the ROM code holds start-up instructions. In fact there are several different programs inside the start-up instructions, but for most users, they are all woven together. You can differentiate between:

1. POST (Power On Self Test)
2. The Setup instructions, which connect with the CMOS instructions
3. BIOS instructions, which connect with the various hardware peripherals
4. The Boot instructions, which call the operating system (DOS, OS/2, or Windows )

All these instructions are in ROM chips, and they are activated one by one during start-up. Let us look at each part.