Chapter 4

Chapter 4 - Chapter 4 Motherboard and BIOS I. a. BIOS b. c....

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Chapter 4 Motherboard and BIOS I. BIOS a. external data bus and address bus along with special support program i. work together to enable the CPU to communicate with all the devices in the PC b. i.e. Keyboard i. connects to external data bus via keyboard controller ii. every time button is pressed, sends coded pattern 1's and 0's to chip called scan code 1. every key has unique scan code a. has own codebook to translate iii. problems: 1. redesigned codebook over years; changed or expanded 2. cant store this program in hard or floppy drive iv. program is stored on read-only memory (ROM) chip c. ROM store programs like RAM chips i. differences: 1. nonvolatile: programs stored aren't erased, even if computer is turned off 2. read-only: once program is stored it cant be changed ii. stores a number of programs to talk to the 8042 (keyboard controller) iii. also stores programs to talk to the floppy drive, hard drive, monitor, etc d. BIOS (basic input/output services) – collective programs stored in ROM chip i. each tiny program – service ii. firmware – programs stored on ROM iii. software – programs stored on erasable media e. When the CPU wants to talk to the 8042, it goes to the ROM chip
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Chapter 4 - Chapter 4 Motherboard and BIOS I. a. BIOS b. c....

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