Chapter3 Introduction to INTEL

X-86 Family

Probable marks: 4

Scope of the syllabus :

Introduction to advanced microprocessors Introduction to X-86 family and study of major attributes of the X-86 fam

processors.

Programming model of X-86 family of microprocessors.

Q.1 Draw a block diagram of 8086 and explain it.

Ans.BIU 1) As shown in the block diagram, Memory

Interface the 8086 C.P.U. is divided into

two independent functional parts: 1. Bus Interface Unit (B.I.U.)

Control Bus

2. Execution Unit (E.U.) 2) The B.I.U. functional part contains

E.S. queue, segment registers and

instruction pointer. 3) Execution unit (E.U.) contains

Instruction C.S. stream

SS byte

D.S. queue

flag register, general purpose registers, stack pointer register and other

pointers, index registers.

P

Control

System

AH AL

BH BL CH CL DH Operand

tlags DL

SP

BP

SI

DI

Fig. 3.1

3-2 Intro. to INTEL X-86 Family

Q.2 Explain in brief 8086 architecture.

Ans. : The 8086 C.P.U. is divided into two independent functional parts:

TPS Computer Science -II

1) Bus Interface Unit (B.I.U.)

) Execution Unit (E.U.)

BusBus Interface Unit (B.I.U.): The B.I.U. sends address, fetches instruction from memory, reads data from

ports/memory and writes data to ports/memory. In other word, B.I.U. handles transfer of data and address on buses for execution unit. It consists of following parts:

Queue: To speed up execution of program, B.I.U. fetches 6 instruction bytes ahead of time from memory and stores them for E.U. in the FIFO register, called queue.

(b) Segment registers: B.I.U. contains following 16-bit segment registers: i) Extra segment (E.S.)

(a)

ii) Code segment (C.S.)

ii) Stack segment (S.S.)

iv) Data segment (D.S.)

These 16-bit segment registers are used to store 16-bit starting address of memory

segment.(c) Instruction pointer (I.P.) : The code segment (C.S.) register holds 16-bit starting

address of segment, from which B.I.U. is fetching register holds 16-bit address of next code byte within code segment.

nstruction code bytes. The IP

II. Execution Unit (E.U.):

Execution unit of 8086 tells B.I.U. where to fetch instructions or data, decodes instruction and executes them. The following sections describe functional part of E.U. :

(a) Flag register: Flag is a flip-flop, which indicate some condition. The 8086 has 16-bit

flag register with 9-active flags.

(b) General purpose registers: 8086 has 8 general purpose registers, labelled AH, AL,

BH, BL, CH, CL, DH and DL. These registers can be used individually for temporary storage of 8-bit data. The AL register is also called as accumulator.

These registers in certain pairs can be used as 16-bit registers. These pairs are AH and AL (AX), BH and BL (BX), CH and CL (CX), DH and DL (DX).

Stack pointer: The 8086 allows us to set 64KB of memory as stack. The 16-bit

starting address of stack is stored in stack pointer. (c)

Explain any two microprocessors in X-86 family in brief.

Explain the following microprocessors in Intel's X-86 family.

Q.3 OR Oct. 04; March 18) Ans.

8086

1) 8086 is a 16-bit microprocessor, introduced by INTEL in 1978.

It was designed to be used as C.P.U. in microcomputer system. It's A.L.U., internal2) registers can work with 16 binary bits at a time.

PS Computer Science - II 3-3 Intro. to INTEL X-86 Family

3) 8086 has 16-bit data bus and 20-bit address bus, so that it can address a physical

memory of 220 = 1048576 1 M Byte memory locations.

The least significant 8 bits of address bus are passed on same eight lines as that of

data bus. This bus is known as multiplexed bus. 4)

In 8086, words are stored in two consecutive bytes. If first byte of word has even 5) address, then 8086 can read it in single operation. Else, it requires two operations.

This processor supports multiplication and division operations. 6) The 80186 is an improved version of 8086. In addition to 16-bit C.P.U., it has

programmable peripheral (1/O) devices integrated in same package. Instruction set

of 80186 is superset of instruction set of 8086.

7)

I) 80286 80286 is a 16-bit microprocessor, introduced in 1982. This advanced version of 8086

is specially designed to be used as a C.P.U. in multiuser/multitasking operating

systems.

1)

2) 80286 has 16-bit data bus and 24-bit address bus. 2) 3) In 1984, IBM introduced PC/AT (Personal Computer/Advanced Technology) 3)

version of its PC using 80286.

286 was having real and protected modes of operation. In real mode, the processor

can address only 1 Mbyte of memory, whereas in protected mode it can address

16 Mbytes of memory.

4)

Another new feature was the ability to work upto 1 Gbyte of virtual memory and 5) yet another feature was added hardware multitasking. The program written for 8086 can run on 80286, operating in its real address mode.

July 2018) 6)

) 80386:

1) The INTEL's 80386 is a 32-bit microprocessor introduced i 1985.

2) 80386 is a logical extension of 80286. It is more highly pipelined.

3) The instruction set of 80386 is a superset of other members of 8086 family.

It has 32-bit data bus and 32-bit nonmultiplexed address bus. It can address a 4)

physical memory of 23 ie. 4 Gbytes. The 80386 memory management allows it to

address 246 or 64 Tbytes.

The 386 can be operated in one of the following memory management modes :

5)

i) Paged mode

ii) Non-paged mode.

6) When operated in paged mode, the 386 switches the paging unit then after the

segment unit. The paging unit allows memory pages of 4 kB each to be swappedn

and out from disk. In non-paged mode, memory management unit operates very

similar to the 286.

6)

Virtual addresses are represented with selected components and an offset 7)

component as they are with 80286.

3-4 TTS Computer

Science - II TPS

Intro. to INTEL X-86 Family 80486

IV

1) It has 32-bit address bus and 32-bit data bus.

Intel's 80486 is a 32-bit microprocessor. It was introduced in 1989.

July 2018

2)

3) The 486 is basically a large integral circuit which contains a fast built-in, a mat coprocessor, a memory management unit (M.M.U.), and an 8 kbyte cache memory. 80486 has DX and SX versions. 4)

5) All 486 processors have 32-bit data bus. SX version does not have on chip-numeric coprocessor.

6 The 486 achieves its high speed operation from its faster clock speeds, internal pipe lined architecture and the use of reduced instruction set computing (RISC) to speed up the internal microcode.

7) 486 also has 486 DX2 and 486 DX4 versions, with double and triple clock speed.

V) Pentium or 80586: Explain the main features of a pentium processor.

OR

Mar.03, 2011, Oct.04)1) Pentium is a 64 bit microprocessor, introduced in 1993.

It has 64 bit data bus and 32-bit address bus. The use of super scalar architecture 2) incorporates a dual-pipe lined processor, which lets the pentium process more than

one instruction per clock cycle.

The addition both of data and code caches on chip is also a feature designed to

3) improve processing speed.

A new advanced computing technique used in pentium is called the branch

prediction, the pentium makes an educated guess where the next instruction

following a conditional instruction will be. This prevents instruction cache from

4)

running dry during conditional instructions.

5) The pentium has 64-bit data bus. This means that it can perform data transfers with

5) an external device twice as fast as a processor with a 32 bit data bus.

Oct. 2011;March2019 Q.4 Compare 80486 and 80586.

Ans. 80586 (Pentium )

Sr. No. 80486

It is 64 bit microprocessor.

1 It is 32 bit Microprocessor.

It's operating speed-25 to 50 MHz It has 50-100 MHz «

It has 8 kbytes cache memory.

It has 50-100 MHz operating speed

2

3 It has 32 bytes cache memory.

It has Internal math co-processor.

4. It has external math co-processor.

It was evolved in 1993.

5. evolved in 1989-SX and

It was 1991-DX version.

TPS Computer Science - II 3-5 Intro. to INTEL X-86 Family

Q.5 Compare any four attributes of 486 DX with Pentium Processor (March 12, 19 Ans.:

Attributes 80486 DX Pentium

Data bus It is 32 bit microprocessor. It is 64 bit microprocessor.

Operating speed (MHz) | Clock frequency 25-50 MHz | Clock frequency 50- 100 mHz

It was evolved in 1993. Introduction date It was evolved in 1991.

It has 32 bytes memory. It has 8 Kbytes memory.

(Oct. 12; March 19 Instruction Cache

Q.6 Compare any four attributes of 80386 & Pentium processor.

Ans. PentiumAttribute 80386

It is 64 bit microprocessor (1) Data bus (2) Instruction cache

It is 32 bit microprocessor

It has 16 byte cache memory It has 8 Kbyte cache

It's data cache is 256 bytes It's data cache is 8 Kbyte (3) Data cache

| (4) | Math co-processor (5) | Internal data word size

(6) Introduction data

It has.external co-processor It has internal co-processor

Word size is 16 bit Word size is 32 bits

Introduced in 1993

50-100 MHz

It was introduced in 1985

()Operating speed in MHz | 16-50 MHz Q.7 List the advanced microprocessors of INTEL X-86 family and mention three

(Oct. 03 attributes of any one of them.

Ans.: List of INTEL X-86 microprocessors family:

8086

80286

80386

80486 INTEL PENTIUM

PENTIUM11 PENTIUMII

PENTIUMIV

For writing attributes of anyone of above please refer Q. No. 3.

Q.8 Explain the advantages of the pentium processor with respect to the following features:

1) Dual pipelining 2) On-chip caches

(Mar. 06, 10, 20, Oct. 08, 10, July 19) 3) Branch prediction 4)64-bit data bus

Ans.

1) Dual pipelining:

The use of super scalar architecture incorporates a dual-pipelining in pentium processor,

which lets pentium to process more than one instruction per clock cycle and achieve a

high level of performance

TS Computer Science

n-chip caches:

data and code

Science - II

3-6 Intro. to INTEL X-86 Family

on-chip caches improves the processing peed of the pentium The

processor.

Branch prediction: The advantage of branch prediction is that, using it, the pentium makes an educated guess where the next instruction following a conditional instruction will

3 Mar 2010)

be.

This prevents the instruction cache from running dry during conditiona i) instruction.

64-bit data bus:

Pentium has 64 bit data bus which allows higher speed of data transfer to it. i) ii) The data transfer speed of pentium is twice as fast as a processor with 32-bit data

bus.

Compare any four attributes of 80286 and Pentium microprocessor. OR Q.9

State four differentiating features among any two X86 family microprocessors. (March 2004, 2010, Oct. 2006)

Ans.

Attributes 80286 PentiumIt is a 16-bit microprocessor. Address bus is 24-bit hence

Database It is a 64-bit microprocessor. Address bus Address bus is 32-bit hence can

can access 16 MB memory. access 4 GB memory. Operating speed (MHz) Clock frequencies 6 MHz Clock frequencies

to 20 MHz. 50 MHz to 100 MHz.

Memory management External InternalMath co-processor External Internal

-

Q.10 Compare any four attributes of 80286 and 80486 Processors. (March 2013; July 18) Ans.

Attributes 80286 80486

Data bus 16 bits 32 bits

Address bus 24 bits 32 bit

6-20MHz 25-50 MHz Operating speed Physical memory address 16 Mbytes 4 bytes

16 bits Internal data word size 32 bits

Introduction data 1982 1989

Ans:. Advance features of X-86 Microprocessor family are as follows :

Programming Model of X-86 Family

State any six advance features of X-86 Micropreocessor Family.Q.11 State any Oct. 2009

) is capable of performing various computing functions and making decisions to change

the sequence of program execution. 2 t is very powerful computing device.

TPS Computer Science - 1I 3-7 Intro. to INTEL X-86 Familk 3) Coprocessor - Advanced microprocessors are supported by numeric coprocessor,

separate CPU which perform arithmetic functions & trigonometric functions. 4) Operating System: Microprocessor works with multiuser & multitasking operatine

system. Virtual Memory: Advanced microprocessor supports virtual memory technique fo storing large volume of data.

Microprocessor includes special instructions & internal h/w which allow a programmar

5)

6) or to write s/w without knowing how much memory is available.

Q.12 Explain the programming model for 32-bit version of X-86 family with suitable diagram. Mar.02, 08, Oct. 05, 07 Ans. 1) The 8088 and 8086 defines the base programming model for the entire X-86 family of advanced microprocessors.

The newer members of X-86 family have greater computing power because they are faster, they use 32-bit registers instead of 16-bit registers and they have advancedaddressing techniques. 3)

2)

Following figure shows programming model for 32-bit version of X-86 family used in 32 bit microprocessor family i.e. in 386, 486 and pentium.: 31 1615 8'7 0 Name

EAX AH AL Acumulator (AX)

EBX BH BL Base Index (BX)

ECX CHCL Count (CX) General EDX DH DL Data (DX) Purpose Registers ESI SI Source Index

EDI DI Destination Index

EBP BP Base pointer

ESP SP Stack pointer

CS Codesegment SS Stack segment Segment

Register ES

DS Data segments

GS

FS Instruction pointer

EIP IP

E lag Flag H FlagL Flag register

4) The programming model of 32-bit version of X-86 family consists of 3 register groups

The first group contains eight general purpose registers called EAX, EBX, ECX, EDX ESI, EDI, ESP and EBP registers. Where E tells us that these registers have extented

length. Each register can be addressed in 1, 8, l6 or 32-bit models. These registers are used to store data during computations.

5)

3-8 TRS

Computer

Science - II Intro. to INTEL X-86 Family

group of registers is the segment group. This group consists of code The second

6) ment, stack segment and four data segment registers. The data segment registers are

DS, ES, FS and G5. These are 16-bit registers. These registers manage operation with

ext oxternal memory. Address computations and data movements are performed here.

The third set of registers consists of Instruction Pointer (1.P.) and flag register.

Q.13 Draw neat labelled diagram and explain the programming model of 16-bit version of X-86 family with register set. Oct. 02, Mar. 2005, 2010, July 2017, 18)

Ans. The 8088 and 8086 defines basic programming model for X-86 family.

1) The 16-bit version for programming model is used in 16-bit microprocessors ot X-86

2) family i.e. in 8088, 8086 and 80286.

The 16-bit version of programming model of X-86 family is shown in the following

figure. 15 87 0 Accumulator

AX AH AL Base Index

BX BH BL Count

General CXCH CL Purpose DX DH | DL

Registers

Data

Source index SI

DI Destination index

BP Base pointer

SP Stack pointer

CS Code segments

SS Stack segmentsSegmentregister DS Data segments

ES

IP Instruction pointer'

Flag register

Programming model of 16-bit version of X-86 family

AS shown in above figure the programming model of 16-bit version of X-86 family

consists of three register groups.

5)

4)

ne first group contains 8-general purpose registers called A, B, C, D, SI, DI, SP and BP

registers. AL, BL, .. indicates lower bytes and AH, BH,... indicates higher bytes. The

full 16-bit registers are referred as AX, BX, CX and DX, where X stands for extended SI

DL, BP, SP registers are always treated as 16-bit registers. These are pointer registers

Decause they are used to point locations within a segment.

3-9 Intro. to INTEL X-86 Family TPS ComputerScience II

6) The second group of registers is the segment group of registers. This group consists of

code segment, stack segment and two data segment. registers. Operation with externat

memory. Address computations and data movements are performed here.

The third group of registers consists of instruction pointer (IP) and flag register.

Enlist the different flags provided by 8086 microprocessor. 7)

Q.14

Ans.: The microprocessor 8086 has 16-bit flag register with 9 active flags, which are shown in

following figure. 10 9 8 76 5 43 2 1 0

UUUU OF DFE TF Sz|uAC UPuCy (U empty) 15 14 13 12 11

where,

Cy- Carry flag.P- Parity flag,

AC- Auxiliary carry flag,

Z-Zero flag,

S-Sign flag, TF -Single step trap, IF- Interrupt flag

DF- direction flag

OF-over flow flag Q.15 Draw a neat labeled diagram of flag register of X86 family. March 2003, Oct. 2005

Ans.

Flag register is used to store special results from data operations. The flag register of X86

family is shown in following figure.

31. 18 17 16 15 14 13 12 11 10 9 8 7 654321 0

Reversed Ac VMRoN1O PL OD TSZ-A-P-C where-

CCarry flag (CF) P Parity flag (PF)

A Auxilliary carry flag (AF)

ZZero flag (ZF) SSign flag (SF) TTrap flag (TF) IInterrupt flag (IF) D-String Direction flag (DF) OOverflow flag (OF)

TPS Computer Science - II

3-10 Intro. to INTEL X-86 Family

JOPL I/O Privileage level N Nested task flag

R Resume flag

VMVirtual mode flag AcAlingment Check flag

8085 microprocessor has 8-bit flag register (0-7) with 5 lags are active.a)

S086/8088 microprocessor has 16-bit flag register, 8 to 11 bits are introduced and b

remaining bits are under fined.

80286 has also 16-bit flag register but 12 to 14 bits are added.S0386 microprocessor has 32 bit flag register with 16 and 17th bits were introduced.

d) 80486 has 32 bit flag register with new 18th bit.

e) Remaining all positions in flag register are reserved.

Select the correct alternative and rewrite the following: Q.16 Which of the following microprocessors does not use multiplexed data/address bus

.

*****

(i) 8085 (ii) 8086 (iii) 80386 (iv) 80186

Ans. (ii) 80386

Pentium processor has .... bit data bus and .. bit address bus.

i) 64, 32 2.

(ii) 32, 64 ii) 32, 32 (iv) 16, 32

Ans. i) 64, 32 The 8086 allows us to set ..... of memory as stack.

(ii) 64 kB 3.

(i) 4 GB (ii) 1 Mb (iv) 16 MB

Ans.: (ii) 64 kB

4 The maximum physical memory can be addressed by 286 is ...

(i) 640 kB (ii) 1 MB (iii) 16 MB (iv) None of these

Ans.: (ii) 16 MB

5. (March 2003)

80386 is a..

i) 8 bit microprocessor

iii) 32 bit microprocessor

(ii) 16 bit microprocessor

(iv) 4 bit microprocessor

Ans. (ii) 32 bitmicroprocessor Oct. 2005) The Intel 80286 isa..... microprocessor.

i) 16 bit

6. (ii) 8 bit (i) 32 bit (iv) None of these

Ans. (i) 16 bit 7. The main difference between the older and newer versions of the aX86 and advanced

microprocessor is that the general purpose register in the newer processor are

64-bit (c) 16-bit

(d) 32-bit (e)

(a) 4-bit (b) 8-bit

Ans. (d) 32 bit You will find data segment registers called the FS and the GS registers on the

microprocessors. (a) 8088

(d) 386

8.

(b) 8086(c) 286

(e) all of the above

Ans.: (d) 386

3-11 Intro. to INTEL X-86 Familv

TPS Computer Science - II

9. The length of the 8088 instruction pointer is.

(b) 8bit (c) 16 bit (d) 32 bit

(a) 4-bit

Ans. (c) 16 bit registers to perform memory locationA separate ALU is used with the

calculations. 10.

(b) Flag (d) General purpose (a) Segment

(c) 16-Instruction pointer

(e) All of the above

(a) Segment A perfect queue or code cache first appeared on the.

(a) 386DX

Ans.

11. (d) 386SX

(h) All of the above 8088 b)8086 (c) 286

(e)(486SX (g) 486DX

Ans. (a) 8088 Some of the newer version of the X86 processor have an on-board memory which is

used to store data as well as prefetched instructions. This is called

(a) An on-chip floating pointer (b) Virtual memory capabilityy

Cache memory

12.

(c) (d) Any of the above

Ans. (c) Cache memory

Logic which analyzes the instruction held in the code cache to anticipate what code

will be needed aftera branch was introduced with the. 13.

(a) 8088

(e) 386DX

Ans. (h) Pentiumn

(b) 8086

()

(c) 286

(8) 486DX

(d) 3865X

(h) Pentium486SX

Internally, the X86 family of advanced microprocessors has a(n)

architecture. 14.

8-bit (b) (d) 32-bit

( 4-bit or 8-bit

(h) 16-bit or 32-bit

(a) 4-bit

16-bit (c) (e) 64-bit

(g) 8-bit or 16-bit

Ans.: (h) 16 bit or 32 bit

The first microprocessor in the X86 family to support an on-chip instruction cache is

() 15.

(a) 8088

(e) 386DX

Ans. (a) 8088

(b) 8086

4865X

286 (d) 386SX

(g)486DX (h) Pentium

The maximum physical memory space which can be addressed by the 286 is

(a) 640 kbytes (b) 1 Mbytes () 16 Mbytes (d) 4 Gbytes 16.

(e) All of the above

Ans.: (c) 16 Mbytes 17. An internal memory management unit (MMU) first appeared on the

(a) 8088

(e) 386DX

(d) 386SX

(h) Pentium (b) 8086 (c) 286

(486SX (g) 486DX

Ans.: (c) 286

3-12 TPS

Computer

Science - 11 Intro. to INTELX-86 Family

On-chip ating ointer arithmetic units first appeared on the 15.

(a) (b)8086 (c) 286 ( Pentium

8088 (d) 386 (e) 486

Ans.: (e) 486

If the processor you are using does not have enough physical memory for the program

19. that is being used, you can use

nrocessor has enough main memory for the program.to make the program believe that the

(a) An on chip floating point processor b) Virtual memory capability

(d) Any of the above (c) Cache memory

Ans.: (b) Virtual memory capability The first X86 advanced microprocessor to use full 32-bit data words was the

20. (b) 386

( Pentium (a) 8088 (c) 8086 (d) 486

(e) 286

Ans.: (d) 486 The Intel 80286 is a _ microprocessor.

(ii) 8 bit 21.

Oct. 2005)

) 16 bit (ii) 32 bit (iv) None of these

Ans.: (i) 16 bit

22. is a 32 bit microprocessor. (OCct. 2007)

i) 8086 ii) 80386 ii) Intel Pentium iv) M68000

Ans (i) 80386

23. The Processor 80386 falls in. generation of MPU. (Oct. 2009 L3.

) First (i) Second (ii) Third iv) Fourth

Ans.: (iv) M68000 Data bus of 80286 MPU is of size 24.

(March2015

) bit (ii) 16 bit (ii) 32 bit (iv) 64 bit

Ans.: (i) 16 bit

The maximum physical memory can be addressed by 80286 microprocessor is

(March 2017) 25.

(ii) 16 MB (iv) 4 KB )

Ans.: (ii) 16 MB 640 KB (ii) 1 MBB

26. July 2017) The duty 32-byte Microprocessor from the following is

) 8086 (ii) 8085

ii) 80386 Ans.: (il) 80386

(iv) 80586

27 Intel 80586 was introduced in . July 2018) i) ii) 1996

Ans.: (ii) 1993

1978 (i) 1993

(iv) 1984