Ch 15: 32-Bit Protected Mode Architecture

Define a System Descriptor in x86 Protected Mode architecture and contrast it with standard code/data segment descriptors.

dd 0x00000000, 0x00008500

Which CPU register is used by BIOS INT 10h VESA functions (VBE 2.0) to return completion status?

mov ax, 0x4F00
mov di, buffer
int 0x10

Complete the following statement regarding Global Descriptor Table (GDT) architecture in x86 Protected Mode: 'The GDT itself is an array of descriptors where each descriptor is an ____-byte entry. The base and limit of GDT is stored in a ____-bit register called the ____. This register is loaded with a special instruction ____ and is given a memory address from where the 48 bits are fetched.'

lgdt [gdt_ptr]

What do the first 16 bits (Bits 0–15) of an 8-byte x86 Protected Mode Segment Descriptor represent?

dd 0x0000FFFF, 0x00CF9A00

Explain the concept of Granularity in x86 Protected Mode segment descriptors and describe the two types of Granularity controlled by the G bit.

; G = 0 -> Limit in Bytes
; G = 1 -> Limit in 4KB Pages