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Unformatted text preview: hexadecimal segment-offset address to a linear
6. In MASM’s ﬂat segmentation model, how many bits hold the address of an instruction or
7. In protected mode, which register references the descriptor for the stack segment?
8. In protected mode, which table contains pointers to memory segments used by a single
9. In the ﬂat segmentation model, which table contains pointers to at least two segments?
10. What is the main advantage to using the paging feature of x86 processors?
11. Challenge: Can you think of a reason why MS-DOS was not designed to support protectedmode programming?
12. Challenge: In real-address mode, demonstrate two segment-offset addresses that point to
the same linear address. For More BS-IT Books, Notes & Assignments visit: www.bsit.zxq.net 48 2.4 Chapter 2 • x86
Downloaded From: www.bsit.zxq.net Processor Architecture Components of a Typical x86 Computer Let us look at how the x86 integrates with other components by examining a typical motherboard conﬁguration and the set of chips that surround the CPU. Then we will discuss memory,
I/O ports, and common device interfaces. Finally, we will show how assembly language programs can perform I/O at different levels of access by tapping into system hardware, ﬁrmware,
and by calling functions in the operating system.
The heart of a microcomputer is its motherboard, a ﬂat circuit board onto which are placed the
computer’s CPU, supporting processors (chipset), main memory, input-output connectors,
power supply connectors, and expansion slots. The various components are connected to each
other by a bus, a set of wires etched directly on the motherboard. Dozens of motherboards are
available on the PC market, varying in expansion capabilities, integrated components, and
speed. The following components have traditionally been found on PC motherboards:
• A CPU socket. Sockets are different shapes and sizes, depending on the type of processor
• Memory slots (SIMM or DIMM) holding small plug-in memory boards
• BIOS (basic input-output system) computer chips, holding system software
• CMOS RAM, with a small circular battery to keep it powered
• Connectors for mass-storage devices such as hard drives and CD-ROMs
• USB connectors for external de...
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This note was uploaded on 11/29/2013 for the course CSE 451 taught by Professor Hussein during the Winter '13 term at Fatih Üniversitesi.
- Winter '13