1. Intel family of Microprocessors
Special Lecture by
Dr. N.Shanmugasundaram,
HOD, ECE Department,
Sri Eshwar College of Engineering,
Coimbatore Dt.

2. Overview of the Presentation
Introduction to Microprocessors
Intel 8085
Intel 8086
Programming and 8086
Peripheral ICs
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3. Introduction to Microprocessors
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4. An Introduction to Microprocessor
What is a Microprocessor ?
An Integrated Circuit (IC) developed using VLSI technology
With a complex digital circuit comprising of adders, registers, …
Capable of processing given Data
According to the Instructions given (program)
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5. An Introduction to Microprocessor
A simple Microprocessor based system:
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6. An Introduction to Microprocessor
Evolution of Intel Microprocessors
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7. An Introduction to Microprocessor
Functional blocks in a Microprocessor:
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8. An Introduction to Microprocessor
A typical Microprocessor based system:
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9. An Introduction to Microprocessor
Buses:
It is a set wires that carries information
(eg. Data, Address, Control signal, etc.)
Multiplexed Buses:
Due to shortage of pins in P IC,
functions of few pins are combined and they are called as Multiplexed Bus.
Such Buses are separated using
ALE signal and a Latch.
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10. An Introduction to Microprocessor
Interrupt:
It is a signal that stops the execution of current program in microprocessor and transfers the program control to a sub-program related to interrupted device.
Hardware Interrupts:
A signal sent by an external device to C
Software Interrupts:
A software instruction for interrupt
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11. An Introduction to Microprocessor
Memory & Address lines:
Relation between Address lines (N) & Memory capacity is
2N = Memory capacity
Addr Lines
Memory Capacity 10
(1 Kilo Byte) 11
(2 Kilo Byte) 12
(4 Kilo Byte) 13
(8 Kilo Byte) 14
(16 Kilo Byte) 15
(32 Kilo Byte) 16
(64 Kilo Byte)
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12. An Introduction to Microprocessor
Program Counter:
16-bit register
holds address of instruction in the program to be executed next.
Eg. PC = 4100H in the figure shown
Stack:
A portion of RAM memory to store data temporarily.
Stack Pointer:
16-bit register
Holds address of stack top
Eg. SP = 5000 H in figure shown
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13. An Introduction to Microprocessor
I/O Mapping:
It is the process by which address is allocated to I/O devices.
The two kinds of mapping are
Memory mapped I/O
I/O mapped I/O
S.No
Memory mapped I/O
I/O mapped I/O 1
16 bit addr of memory is given to I/O device
Separate 8 bit addr is given to I/O device 2
Each I/O device is treated like a memory location and they are accessed using instructions related to memory operations.
All I/O devices are accessed
using only two instructions viz., IN and OUT. 3
Data can be transferred between
I/O devices and all registers in P.
I/O devices and accumulator only in P. 4
Only Memory Read & Write machine cycles are involved during data transfer with I/O devices.
Only I/O Read & Write machine cycles are involved during data transfer with I/O devices. 5
Large number of I/O devices
can be connected in this scheme.
Only maximum of 256(=28 ) I/O devices
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14. Intel 8085
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15. Intel 8085 Features of Intel 8085: 40-pin DIP chip designed using HMOS
8-bit data and 16-bit address bus
With 16-bit address, can access 216 = = 64KB memory locations
8-bit Flag register with 5 flags
Operates with power supply of +5 volts and Gnd
Max Clock frequency is 12 MHz
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16. Intel 8085
Pin Diagram:
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17. Intel 8085
Architecture:
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18. Intel 8085
Flag register:
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19. Register Organization:
Intel 8085
Register Organization:
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20. An Introduction to Microprocessor
Interrupt:
It is a signal that stops the execution of current program in microprocessor and transfers the program control to a sub-program related to interrupted device.
Hardware Interrupts:
TRAP
RST 7.5
RST 6.5
RST 5.5
INTR
Software Interrupts:
RST n (n = 0 ~ 7)
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21. Intel 8085 Instruction format:
The 8085 has 74 instructions and 246 combinations in it.
8085 instructions size is 1 byte, 2 bytes and 3 three bytes.
Each instruction of 8085 has 1 byte opcode.
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22. Intel 8085 Addressing Modes:
Every instruction of a program operates on a data.
The method of specifying the data to be operated by the instruction is called Addressing.
The 8085 has the following 5 different types of addressing.
1. Immediate Addressing Eg. ADI 15H
2. Direct Addressing Eg. LDA 4200H
3. Register Addressing Eg. MOV A, B
4. Register Indirect Addressing Eg. LDAX B
5. Implied Addressing Eg. CMA
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23. Intel 8085 Instruction set: Data Transfer Arithmetic Logical Branching
Machine control
MOV Rs, Rd
MOV M, Rs
MOV Rd, M
MVI Rd, d8
MVI M, d8
LDA a16
LDAX rp
LHLD a16
LXI rp, d16
STA a16
STAX rp
SHLD a16
SPHL
XTHL
XCHG
PUSH rp
PUSH PSW
POP rp
POP PSW
IN a8
OUT a8
ADD Rs
ADD M
ADI d8
ADC Rs
ADC M
ACI d8
SUB Rs
SUB M
SUI d8
SBB Rs
SBB M
SBI d8
INR Rs
INR M
INX rp
DCR Rs
DCR M
DCX rp
ANA Rs
ANA M
ANI d8
ORA Rs
ORA M
ORI d8
XRA Rs
XRA M
XRI d8
CMP Rs
CMP M
CPI d8
RAL RLC
RAR
RRC
CMA
CMC
STC
JMP a16
J<cond> a16
CALL a16
C <cond> a16
RET
RETI
PCHL
RST n EI DI
SIM
RIM
NOP
HLT 21 20 19 8 6
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24. Machine Cycles and Timing Diagram:
Intel 8085
Machine Cycles and Timing Diagram:
The machine cycles are the basic operations performed by the processor, while instructions are executed.
The time taken for performing each machine cycle is expressed
in terms of T-states.
One T-state is the time period of one clock cycle of the microprocessor.
The various machine cycles are
1. Opcode fetch …………… / 6 T
2. Memory Read …………… T
3. Memory Write …………… T
4. I/O Read ………………… T
5. I/O Write ………………… T
6. Interrupt Acknowledge - 6 / 12 T
7. Bus Idle …………………… - 2 / 3 T
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25. Instruction Execution & Machine Cylces:
Intel 8085
Instruction Execution & Machine Cylces:
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26. Intel 8085 Memory Interfacing:
Draw the circuit diagram of an 8085 system, having a 4 KB EPROM and two 8 KB RAM ICs.
The starting address of EPROM is 0000H and RAM is 4000 & 8000H.
The address of the decoder circuits should be clearly shown.
Solution:
EPROM - 4 KB (Address lines required is 12 – A0 to A11 )
RAM-I - 8 KB (Address lines required is 13 – A0 to A12 )
RAM-II - 8 KB (Address lines required is 13 – A0 to A12 )
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27. Intel 8085 Memory Interfacing: Mapping of Addresses to Memory ICs
Binary Address
Hex Address
A15
A14
A13
A12
A11
A10 A9 A8 A7 A6 A5 A4 A3 A2 A1 A0
EPROM
4 KB . x 1
0000
0001
0FFF
RAM-I
8 KB
4000
4001
5FFF
RAM-II
8000
8001
9FFF
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28. Intel 8085
Memory Interfacing:
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29. Intel 8086
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30. Intel 8086 Features: 40 pin DIP IC - HMOS technology 16-bit Data bus
20-bit address bus.
More memory addressing capability (220 = 1MB)
16 bit Flag register with 9 Flags
Can be operated in Minimum mode and Maximum mode
Has two stage pipelined architecture
No internal clock generation
Operates on +5V supply voltage
Has more powerful instruction set
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31. Intel 8086
Pin Diagram:
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32. Pipelined Architecture:
Intel 8086
Pipelined Architecture:
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33. Intel 8086
Architecture:
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34. Register Organization:
Intel 8086
Register Organization:
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35. Intel 8086
Flag register:
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36. Intel 8086
Memory Segmentation:
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37. Physical address calculation:
Intel 8086
Physical address calculation:
20-bit physical address of memory is generated
by adding the segment address and offset address.
Eg. CS = 1234 H
IP = H
Physical Address = (Segment Address x 10) + Offset
= ( 1234 x 10 ) =
= H
Note: Segment address is left shifted 4 times instead of multiplying by 10.
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38. Minimum mode Configuration:
Intel 8086
Minimum mode Configuration:
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39. Maximum mode configuration:
Intel 8086
Maximum mode configuration:
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40. Intel 8086 Addressing Modes:
Addressing modes for accessing Immediate and Register data.
Addressing modes for accessing data in Memory.
Addressing modes for accessing I/O ports.
Relative Addressing mode.
Implied Addressing mode.
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41. Intel 8086 Addressing Modes:
1. Addressing modes for accessing Immediate and Register data.
(i) Register addressing mode: Eg. MOV BX, CX
MOV CL, BL
(ii) Immediate addressing mode: Eg. MOV BL, 26H
MOV CX, 4567H
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42. Intel 8086 Addressing Modes:
2. Addressing modes for accessing data in Memory.
(i) Direct addressing mode: Eg. : MOV CX, [9823H]
(ii) Register indirect addressing mode: Eg. : MOV CX, [BX]
(iii) Based Addressing Mode: Eg. : MOV AX, [BX + 08H]
(iv) Indexed Addressing Mode: Eg. : MOV AX, [DI + 08H]
(v) Based Indexed Addressing Mode: Eg. : MOV AX, [BX +DI + 08H]
(vi) String Addressing Mode: Eg. : MOVS BYTE
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43. Intel 8086 Addressing Modes:
3. Addressing modes for accessing Data in I/O Ports.
(i) Direct I/O port Addressing Mode: Eg. : IN AL, [09H]
(ii) Indirect I/O port Addressing Mode: Eg. : IN AL, [CL]
4. Relative Addressing mode
Eg. : JZ 0AH
5. Implied Addressing mode
Eg. : CLD
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44. The 8086 instruction set is classified as follows.
Intel 8086
Instruction set:
The 8086 instruction set is classified as follows.
Data Transfer Instructions
Arithmetic Instructions
Bit manipulation instruction.
String instruction.
Program execution transfer instruction.
Processor control instruction.
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45. Data Transfer Instructions:
Intel
Data Transfer Instructions:
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46. Arithmetic Instructions:
Intel
Arithmetic Instructions:
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47. Arithmetic Instructions:
Intel
Arithmetic Instructions:
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48. Bit Manipulation (Logical) Instructions:
Intel
Bit Manipulation (Logical) Instructions:
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49. Program Execution Transfer Instructions:
Intel
Program Execution Transfer Instructions:
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50. String Manipulation Instructions:
Intel
String Manipulation Instructions:
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51. Iteration Instructions:
Intel
Iteration Instructions:
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52. Process Control Instructions:
Intel
Process Control Instructions:
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53. External Hardware Synchronization Instructions:
Intel
External Hardware Synchronization Instructions:
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54. Programming Intel 8085 & 8086
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55. Steps in Programming for a Microprocessor Understand the problem
Intel 8085 &
Programming :
Steps in Programming for a Microprocessor
Understand the problem
Device an algorithm for the given problem
Identify the instructions that suits for the steps in algorithm
Validate the program
Verify the results
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56. 8085 – Programming Exercise #1
Intel 8085 &
Programming :
8085 – Programming Exercise #1
Write an ALP for 8085 to multiply two 8-bit numbers.
Assume two 8-bit data are in memory locations 4200 & 4201.
LOGIC:
There is no direct multiplication instruction in So, Multiplication is done through repeated addition Example: 3 x 2 = (3 + 3) or (2+2+2)
Take two 8-bit numbers from memory and store it in 2 registers (B & C).
Clear Acc and start adding first number for second number of times
Store the result (in Acc) in another memory location (4202)
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57. Write an ALP for 8085 to multiply two 8-bit numbers.
Intel 8085 &
Programming :
Write an ALP for 8085 to multiply two 8-bit numbers.
LDA 4200
MOV B, A
LDA 4201
MOV C, A
MVI A, 00
ADD B (Loop)
DCR C
JNZ Loop
STA 4202
HLT
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58. Write an ALP for 8085 to divide two 8-bit numbers.
Intel 8085 &
Programming #2:
Write an ALP for 8085 to divide two 8-bit numbers.
Assume data is available in
memory location 4200 & 4201.
Write a ALP on your own
for given flow chart
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59. 8086 – Programming Exercise #3
Intel 8085 &
Programming :
8086 – Programming Exercise #3
Write an ALP for 8086 to find largest number in an array.
Assume location 4200 has count (size of array), followed by array elements.
LOGIC:
1: Take first number (count) from memory and store it in CL register.
2: Clear Acc
3: start comparing from first array element
4: If array element greater than Acc; copy memory content to Acc or otherwise ignore and go to next step.
5: Decrement count in CL and stop comparing if CL =0 and go to step 7 or otherwise go to next step.
6: Go to next memory location and repeat from step 3
7: Store the result in memory and stop
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60. Write an ALP for 8086 to find largest number in an array.
Intel 8085 &
Programming :
Write an ALP for 8086 to find largest number in an array.
MOV CL, [4200]
MOV BX, 4201
MOV AL, 00
CMP M, AL (Loop)
JC Next
MOV AL, [BX]
INC BX (Next)
DEC CL
JNZ Loop
MOV 4500, AL
HLT
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61. 8086 – Programming Exercise #4
Intel 8085 &
Programming :
8086 – Programming Exercise #4
Write an ALP for 8086 for copying string.
ALGORITHM:
Start the program.
Set the SI to point the source array and DI at destination location.
Move the string size to CX register.
Direction Flag is cleared so that SI & DI will auto increment after each loop.
Move the bytes of the string using MOVSB instruction.
Stop the program.
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62. Write an ALP for 8086 for copying string.
Intel 8085 &
Programming #4:
Write an ALP for 8086 for copying string.
MOV SI, Source
MOV DI, Destination
MOV CX, 000AH
CLD
MOVSB (Next)
LOOP Next
HLT
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63. Peripheral ICs
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64. Peripheral ICs and Its Interface
PPI
KBD & DISPLAY Controller
TIMER
ADC
DAC
CRT Interface
Printer Interface
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65. Intel 8255 - Programmable Peripheral Interface (PPI)
Intel 8255 is a programmable peripheral interface chip designed for parallel communication between microprocessor and I/O devices, which have a speed mismatch between each other.
Features of 8255:
It has three 8-bit ports (Port A, B, C)
It can be operated in three different modes in I/O mode and in BSR mode
The three operating modes in I/O mode are
Mode 0 - Simple I/O port
Mode l - Handshake I/O port
Mode 2 - Bidirectional I/O port.
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66. Intel 8255 - Programmable Peripheral Interface (PPI)
Internal block diagram of 8255
The ports are grouped as Group A and Group B.
The group A has port A, port Cupper and its control circuit.
The group B has port B, port Clower and its control circuit.
The Read/Write control logic requires six control signals.
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67. Intel 8255 - Programmable Peripheral Interface (PPI)
For operating in I/0 mode;
I/O mode - control word is send to control register.
The format of the I/0 mode set control word is shown below.
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68. Intel 8255 - Programmable Peripheral Interface (PPI)
For setting/resetting (BSR mode) of a pin of port C,
the bit set/ reset control word is sent to control register.
The format of bit set/reset control word is shown below.
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69. Intel 8279 - Keyboard and Display Controller
IC 8279 is a dedicated controller specially developed for keyboard/ display interfacing in 8085/8086/8088 microprocessor based system.
It relieves the processor from the following time consuming task like keyboard scanning and display refreshing.
Keyboard scanning
Key debouncing
Key code generation
Sending display code to LED
Display refreshing
The processor time will be utilized, as the above functions have to be performed continuously in specified time intervals.
To overcome this problem, the dedicated Keyboard/Display controller such as INTEL 8279 can be employed in the system.
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70. Intel 8279 - Keyboard and Display Controller
Features of are
Simultaneous keyboard and display operations.
2-Key lockout or N-key rollover with contact debounce.
Scanned keyboard mode.
Scanned sensor mode.
Strobed input entry mode.
8-character keyboard FIFO
16-character display
Mode programmable from CPU
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71. Intel 8279 - Keyboard and Display Controller
Block diagram of 8279
The functional block diagram of 8279 is shown in figure below.
The four major sections of 8279 are keyboard, scan, display and CPU interface.
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72. Intel 8279 - Keyboard and Display Controller
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73. Intel 8279 - Keyboard and Display Controller
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74. Intel 8253 - Programmable Interval Timer
The 8253 is a Programmable interval timer/counter.
The 8253 includes three identical 16-bit counters that can operate independently in any of the six modes.
It is PQC based in a 24 pin o/p and required a single +5v Power Supply.
The 8254 is an upgraded version of the 8253 and the pins are compatible.
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75. Intel 8253 - Programmable Interval Timer
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76. Intel 8253 - Programmable Interval Timer
MODE 0 - Interrupt on Terminal Count
When this mode is set, the output will be low. Loading the count register with a value will cause the output to remain low and the counter will start counting down. When the counter reaches 0 the output will go high and remain high until the counter is reprogrammed.
MODE 1 - Programmable One-Shot
The output will go low, once the counter has been loaded, and will go high once terminal count has been reached. Once terminal count has been reached it can be triggered again.
MODE 2 - Rate Generator
It is a standard divide-by-N counter. The output will be low for one period of the input clock then it will remain high for the next period in the counter. This cycle will keep repeating.
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77. Intel 8253 - Programmable Interval Timer
MODE 3 - Square Wave Rate Generator
Similar to mode 2, except the output will remain high until one half of the count has been completed and then low for the other half.
MODE 4 - Software Triggered Strobe
After the mode is set the output will be high. Once the count is loaded it will start counting, and will go low once terminal count is reached.
MODE 5 - Hardware Triggered Strobe
Hardware triggered strobe. Similar to mode 5, but it waits for a hardware trigger signal before starting to count. Modes 1 and 5 require the 8253 gate pin to go ‘high’ in order to start counting.
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78. Intel 8253 - Programmable Interval Timer
CONTROL FORMAT:
SC1
SC0
RL1
RL0 M2 M1 M0
BCD
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79. A/D Converter
In many applications, an analog device has to be interfaced to digital system.
But the digital devices cannot accept the analog signals directly and so the analog signals are converted into equivalent digital signal (data) using ADC.
The first group includes
successive-approximation, counter and flash type converters.
The second group includes
integrator converters and voltage to frequency converters.
The trade-off between the two techniques is based on Accuracy Vs Speed.
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80. A/D Converter
The resolution of the converter is the minimum analog value that can be represented by the digital data. R = Vref / 2N
The conversion time is defined as the total time required to convert an analog signal into its digital equivalent. (It depends on the conversion technique and the propagation delay in various circuits).
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81. A/D Converter
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82. A/D Converter
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83. D/A Converter
Basically the microprocessor system can produce only digital signals In many applications, the microprocessor has to produce analog signals for controlling certain analog devices.
In order to convert the digital signal to analog signal a Digital-to-Analog Converter (DAC) has to be employed.
For example,
Consider an 8-bit DAC with reference analog voltage of 5 volts.
Now the resolution of the DAC is (1/28) x 5 volts.
The 8-bit digital input can take, = 256 different values.
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84. D/A Converter
The switches in the circuit of figure above can be transistors which connects the resistance either to ground or Vref.
The resistors are connected in such a way that for any number of inputs, the total current is in binary proportion.
The operational amplifier converts the current to a voltage signal V0, which can be calculated from the following equation.
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85. D/A Converter
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86. D/A Converter The typical settling time of DAC0800 is 150ns.
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87. Thank you For your patience… Dr. N.Shanmugasundaram, ECE Department,
For Queries & Clarifications, Contact
Dr. N.Shanmugasundaram,
ECE Department,
Sri Eshwar College of Engineering,
Coimbatore District
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