E-LESSON-10

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B.C.A 2 All right are reserved with CU-IDOL Digital Circuits and Logic Designs Course Code: BCA111 Semester: First SLM Units: e-Lesson No: 10 7 www.cuidol.in Unit-10 (BCA111)

MICROPROCESSOR 1 33 OBJECTIVES IINNTTRROODDUUCCTTIIOONN After studying this unit, you will be able to: In this session we are going to learn about: • Define microprocessor • Define microprocessor • Draw the block diagram of microprocessor 8085 • Draw the block diagram of microprocessor 8085 • Explain functioning of different components of • Explain functioning of different components of microprocessor 8085 microprocessor 8085 • Describe pin diagram of microprocessor 8085 • Describe pin diagram of microprocessor 8085 www.cuidol.in Unit-10 (BCA111) IANlSlTIrTigUhTtEaOreF DreIsSTeArvNeCdEwAiNthDCOUN-LIDINOELLEARNING

TOPICS TO BE COVERED 4 •Historical Background of Microprocessor and Application of Microprocessor •8085 Microprocessor Architecture •Pin Diagram of 8085 •Summary www.cuidol.in Unit-10 (BCA111) All right are reserved with CU-IDOL

5 www.cuidol.in Unit-10 (BCA111) All right are reserved with CU-IDOL

8085 Microprocessor Architecture 6 www.cuidol.in Unit-10 (BCA111) All right are reserved with CU-IDOL

8085 architecture() 7 (a) Control Unit • Generates signals within uP to carry out the instruction, which has been decoded. In reality, it • causes certain connections between blocks of the uP to be opened or closed, so that data goes • where it is required, and so that ALU operations occur. (b) Arithmetic Logic Unit • The ALU performs the actual numerical and logic operation such as ‘add’, ‘subtract’, ‘AND’, • ‘OR’, etc. Uses data from memory and from Accumulator to perform arithmetic. Always stores • result of operation in Accumulator. www.cuidol.in Unit-10 (BCA111) All right are reserved with CU-IDOL

Registersap) 8 www.cuidol.in Unit-10 (BCA111) All right are reserved with CU-IDOL

Registers-) 9 • In addition, it has two 16-bit registers: the stack pointer and the program counter. They are • described briefly as follows. • The 8085/8080A has six general-purpose registers to store 8-bit data; these are identified as • B, C, D, E, H, and L as shown in the figure 10.1. They can be combined as register pairs – BC, • DE, and HL – to perform some 16-bit operations. The programmer can use these registers to store • or copy data into the registers by using data copy instructions. www.cuidol.in Unit-10 (BCA111) All right are reserved with CU-IDOL

Flag 10 • The ALU includes five flip-flops, which are set or reset after an operation according to data • conditions of the result in the accumulator and other registers. They are called • Zero (Z), • Carry (CY), • Sign (S), • Parity (P), • Auxiliary Carry (AC) flags. • They are listed in the Table and their bit positions in the flag register are shown in the Figure below. www.cuidol.in Unit-10 (BCA111) All right are reserved with CU-IDOL

Flag Registers) 11 www.cuidol.in Unit-10 (BCA111) All right are reserved with CU-IDOL

Registers 12 Program Counter (PC) • This 16-bit register deals with sequencing the execution of instructions. This register is a memory pointer. Memory locations have 16-bit addresses, and that is why this is a 16-bit register. • The microprocessor uses this register to sequence the execution of the instructions. The function of the program counter is to point to the memory address from which the next byte is to be fetched. When a byte (machine code) is being fetched, the program counter is incremented by one to point to the next memory location. • (g) Stack Pointer (SP) • The stack pointer is also a 16-bit register used as a memory pointer. It points to a memory • location in R/W memory, called the stack. The beginning of the stack is defined by loading 16-bit • address in the stack pointer. The stack concept is explained in the unit “Stack and Subroutines.” www.cuidol.in Unit-10 (BCA111) All right are reserved with CU-IDOL

Registers 13 • Instruction Register/Decoder • Temporary store for the current instruction of a program. Latest instruction sent here from memory prior to execution. Decoder then takes instruction and ‘decodes’ or interprets the instruction. Decoded instruction then passed to next stage. • Memory Address Register • Holds address, received from PC, of next program instruction. Feeds the address bus with addresses of location of the program under execution. • Control Generator • Generates signals within uP to carry out the instruction which has been decoded. In reality causes certain connections between blocks of the uP to be opened or closed, so that data goes where it is required, and so ALU operations occur. www.cuidol.in Unit-10 (BCA111) All right are reserved with CU-IDOL

8085 Pin diagram 14 www.cuidol.in Unit-10 (BCA111) All right are reserved with CU-IDOL

Multiple Choice Questions 1. In an instruction of 8085 microprocessor, how many bytes are present? 15 (a) 1 or 2 (b) 1,2 or 3 (c) 1 only (d) 2 or 3 2. Which one of the following addressing technique is not used in the 8085 microprocessor? (a) register (b) immediate (c) register indirect (d) relative 3. Which of the following register of 8085 microprocessor is not a part of programming language? (a) Instruction register (b) memory addressing (c) status register (d) temporary register Answers: 1.(b) 2.(d) 3(c) www.cuidol.in Unit-10 (BCA111) All right are reserved with CU-IDOL

SUMMARY Let us recapitulate the important concepts discussed in this session: 16 •Control Unit - generates signals within uP to carry out the instruction, which has been decoded. In reality, it causes certain connections between blocks of the uP to be opened or closed, so that data goes where it is required, and so that ALU operations occur. •The ALU performs the actual numerical and logic operation such as ‘add’, ‘subtract’, ‘AND’, ‘OR’, etc. Uses data from memory and from Accumulator to perform arithmetic. Always stores result of operation in Accumulator. •The 8085/8080A has six general-purpose registers to store 8-bit data; these are identified as B, C, D, E, H, and L. They can be combined as register pairs – BC, DE, and HL – to perform some 16-bit operations. The programmer can use these registers to store or copy data into the registers by using data copy instructions. •The ALU includes five flip-flops, which are set or reset after an operation according to data conditions of the result in the accumulator and other registers. •This 16-bit register deals with sequencing the execution of instructions. This register is a memory pointer. Memory locations have 16-bit addresses, and that is why this is a 16-bit register. www.cuidol.in Unit-10 (BCA111) All right are reserved with CU-IDOL

FREQUENTLY ASKED QUESTION 17 Q1. Describe the 8085 microprocessor general purpose registers. Ans: The 8085/8080A has six general-purpose registers to store 8-bit data; these are identified as B, C, D, E, H, and L. For further details refer SLM unit 10. Q2. Explain the five flags of 8085 microprocessor. Ans: The five flags of 8085 microprocessor are - Zero (Z), Carry (CY), Sign (S), Parity (P), Auxiliary Carry (AC) flags. For further details refer SLM unit 10. Q3. What is stack pointer? Describe the pin diagram of 8085 microprocessor. Ans: The stack pointer is also a 16-bit register used as a memory pointer. For further details refer SLM unit 10. www.cuidol.in Unit-10 (BCA111) All right are reserved with CU-IDOL

References 18 1.https://www.google.com/search?q=microprocessor&rlz=1C1CHBF_enIN862IN862&oq=microproces sor&aqs=chrome..69i57j0l4j69i60l3.8450j0j7&sourceid=chrome&ie=UTF-8 2. https://www.tutorialspoint.com/microprocessor/microprocessor_overview.htm 3. https://www.techwalla.com/articles/why-is-a-microprocessor-important 4. https://inspirit.net.in/viewer/Li9ib29rcy9hY2FkZW1pYy84MDg1IE1pY3JvcHJvY2V zc29yIC0gUmFtZXNoIEdhb25rYXIucGRm www.cuidol.in Unit-10 (BCA111) All right are reserved with CU-IDOL

19 THANK YOU www.cuidol.in MCA611 All right are reserved with CU-IDOL Unit-10 (BCA111)