IntroductionPart 1

• The Microprocessor Based Systems Memory and I/O System Microprocessor

MicroprocessorMicroprocessor I/O SystemI/O SystemMemory SystemMemory System

Buses

Dynamic RAM (DRAM)Static RAMCacheRead-Only (ROM)Flash MemoryEEPROMSDRAMRAMBVS

808680888018680188802868038680486PentiumPentium ProPentium IIPentium IIIPentium 4

PrinterSerial CommunicationsFloppy Disk DriveHard Disk DriveMouseCD-ROM DrivePlotterKeyboardMonitorTape BackupScannerDVD

The Block Diagram of a Microprocessor-Based Computer System

The Memory Map of Personal Computers

15M bytes in the 80286 or 80386X31M bytes in the 80386SL/SLC63M bytes in the 80386EX4095M bytes in the 80386DX, 80486, and Pentium64G bytes in the Pentium Pro, Pentium II, Pentium III, and Pentium 4

1M bytes of real (conventional) Memory

System Area384K bytes

TPA640K bytes

Extended Memory

The transient program area (TPA) holds the DOS operating system and other programs that control the computer system. The TPA also stores any currently active or inactive DOS application programs.

The Memory Map of the TPA in a Personal Computer (vary between systems)

COMMAND.COM

Free TPA

Device driversSuch as MOUSE.SYS

IO.SYS program

BIOS communications area

MSDOS program

DOS communications area

Interrupt vectors00000

00400

00500

00700

01160

02350MSDOS program

08490

08E30

9FFF0

9FFFF • The Interrupt vectors access various features of the DOS, BIOS (basic I/O system), and applications.

• The System BIOS and DOS communication areas contain transient data used by programs to access I/O devices and the internal features of the computer system.

• The IO.SYS is a program that loads into the TPA from the disk whenever an MSDOS or PCDOS system is started. It contains programs that allow DOS to use the keyboard, video display, printer, and other I/O devices often found in the computer system. The I/O.SYS program links DOS to the Programs stored on the system BIOS ROM.

• DOS occupies two areas of memory: One is 16 bytes in length and is located at the top of the TPA, and the other is much larger and is located near the bottom of the TPA. The DOS program controls the operation of the computer system. The size of the DOS area depends on the version of DOS installed in the computer and how it is installed

The Memory Map of the TPA in a Personal Computer (vary between systems)

COMMAND.COM

Free TPA

Device driversSuch as MOUSE.SYS

IO.SYS program

BIOS communications area

MSDOS program

DOS communications area

Interrupt vectors00000

00400

00500

00700

01160

02350MSDOS program

08490

08E30

9FFF0

9FFFF • The size of the driver area and number of drivers change from one computer to another . Drivers are programs that control installable I/O devices such as a mouse, scanner, CD-ROM, …

• The COMMAND.COM program (command processor) controls the operation of the computer from the keyboard when operated in the DOS mode. The COMMAND.COM program processes the DOS commands as they are typed from the keyboard.

• The free TPA area holds DOS application programs as they are executed. These application programs include word processors, spreadsheet programs, …etc.TPA also holds TSR (terminate and stay resident) programs that remain in memory in an inactive state until activated by a hot-key sequence or another event such as an interrupt.

The Memory Map of the System Area in a Personal Computer (vary between systems)

Basic Language ROM (only on new PCS)

Video RAM(text area)

Video RAM(graphics area)

BIOS System ROM

A0000

B0000

C0000

Free Area

Hard Disk Controller ROMLAN Controller ROM

C8000

F0000

Video BIOS ROM

E0000

FFFFF

Memory Hierarchy

Registers

L1 Cache

L2 Cache

Main Memory

Smaller, Faster, and More Expensive

Larger, Slower, and Cheaper

The Microprocessor

The microprocessor (sometimes referred as the CPU) is the controlling element in a computer system.

The microprocessor controls memory and I/O through a series of connections called buses.

The microprocessor performs three main tasks for the computer system:

Data transfer between itself and the memory or I/O systems. Simple arithmetic and logic operations. Program flow via simple decisions.

The power of the microprocessor is in its capability to execute hundreds of millions of instructions per second from a program or

software (group of instructions) stored in the memory system.

Arithmetic and Logic Operations Executed by Intel Family of Microprocessors

Operation Comment

Addition

Subtraction

Multiplication

Division

AND Logical Multiplication

OR Logical Addition

NOT Logical Inversion

NEG Arithmetic Inversion

Shift

Rotate

Decision Comment

ZeroTest a number for zero or not-zero

SignTest a number for positive or negative

CarryTest for a carry after addition or a borrow after subtraction

ParityTest a number for an even or an odd number of ones

Overflow

Test for an overflow that indicates an invalid signed result after addition or subtraction

Decision-making capabilities of the Intel Family of

Microprocessors

Buses

A bus is a common group of wires that interconnect components in a computer system. The buses transfer address, data, and control information between the microprocessor and its memory and I/O systems.

The buses: Select an I/O or memory device. Transfer data between an I/O device or memory and the

microprocessor. Controls the I/O and memory system through instructions that

are stored in the memory and executed by the microprocessor.

µp

MWTCMRDCIOWCIORC

Read-only memory

ROM

Read-only memory

ROM

Read/write memory

RAM

Read/write memory

RAM

KeyboardKeyboard PrinterPrinter

Address Bus

Data Bus

Control Bus

Requests a memory location from the memory or an I/O location from the I/O devices.

Transfers information between the microprocessor and its memory and I/O address space.

Contains lines that select the memory or I/O and cause them to perform a read or write operation.

Intel MicroprocessorsMicroprocessor

Data Bus Width

Address Bus Width

Memory Size

8086 16 20 1M

8088 8 20 1M

80186 16 20 1M

80188 8 20 1M

80286 16 24 16M

80386SX 16 24 16M

80386DX 32 32 4G

80386EX 16 26 64M

80486 32 32 4G

Pentium 64 32 4G

Pentium OverDrive 32 32 4G

Pentium Pro 64 32 4G

Pentium Pro 64 36 64G

Pentium II 64 32 4G

Pentium II, Pentium III, Pentium 4

64 36 64G

The memory size depends on the address bus width, for example 20bit address bus means that the processor can address memory size up to 2^20= 1048576 byte /1024 1024 KB (1MB)