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9. Which ﬂag is set when an arithmetic or logical operation generates a negative result?
10. Which part of the CPU performs ﬂoating-point arithmetic?
11. How many bits long are the FPU data registers?
12. Which Intel processor was the ﬁrst member of the IA-32 family?
13. Which Intel processor ﬁrst introduced superscalar execution?
14. Which Intel processor ﬁrst used MMX technology?
15. Describe the CISC design approach.
16. Describe the RISC design approach. 2.3 x86 Memory Management x86 processors manage memory according to the basic modes of operation discussed in
Section 2.2.1. Protected mode is the most robust and powerful, but it does restrict application
programs from directly accessing system hardware.
In real-address mode, only 1 MByte of memory can be addressed, from hexadecimal 00000
to FFFFF. The processor can run only one program at a time, but it can momentarily interrupt
that program to process requests (called interrupts) from peripherals. Application programs are
permitted to access any memory location, including addresses that are linked directly to system
hardware. The MS-DOS operating system runs in real-address mode, and Windows 95 and 98
can be booted into this mode.
In protected mode, the processor can run multiple programs at the same time. It assigns each
process (running program) a total of 4 GByte of memory. Each program can be assigned its own
reserved memory area, and programs are prevented from accidentally accessing each other’s
code and data. MS-Windows and Linux run in protected mode.
In virtual-8086 mode, the computer runs in protected mode and creates a virtual 8086
machine with its own 1-MByte address space that simulates an 80x86 computer running in realaddress mode. Windows NT and 2000, for example, create a virtual 8086 machine when you
open a Command window. You can run many such windows at the same time, and each is protected from the actions of the others. Some MS-DOS programs that make direct references to
computer hardware will not run in this mode under Windows NT, 2000, and XP.
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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