18-01-2016, 04:30 PM
1. What is Microprocessor? Give the power supply & clock frequency of 8085
A microprocessor is a multipurpose, programmable logic device that reads binary
instructions from a storage device called memory accepts binary data as input and processes data
according to those instructions and provides result as output. The power supply of 8085 is +5V
and clock frequency in 3MHz.
2. List few applications of microprocessor-based system.
It is used:
i. For measurements, display and control of current, voltage,
temperature, pressure, etc.
ii. For traffic control and industrial tool control.
iii. For speed control of machines.
3. What are the functions of an accumulator?
The accumulator is the register associated with the ALU operations and sometimes I/O
operations. It is an integral part of ALU. It holds one of data to be processed by ALU. It also
temporarily stores the result of the operation performed by the ALU.
4. List the 16 – bit registers of 8085 microprocessor.
Stack pointer (SP) and Program counter (PC).
5. List the allowed register pairs of 8085.
• B-C register pair
• D-E register pair
• H-L register pair
6. Mention the purpose of SID and SOD lines
SID (Serial input data line):
It is an input line through which the microprocessor accepts serial data.
SOD (Serial output data line):
It is an output line through which the microprocessor sends output serial data.
7. What is the function of IO/M signal in the 8085?
It is a status signal. It is used to differentiate between memory locations and I/O
operations.When this signal is low (IO/M = 0) it denotes the memory related operations. When
this signal is high (IO/M = 1) it denotes an I/O operation.
8. List out the five categories of the 8085 instructions. Give examples of the instructions
for each group.
• Data transfer group – MOV, MVI, LXI.
• Arithmetic group – ADD, SUB, INR.
• Logical group –ANA, XRA, CMP.
• Branch group – JMP, JNZ, CALL.
• Stack I/O and Machine control group – PUSH, POP, IN, HLT.
9. Explain the difference between a JMP instruction and CALL instruction.
A JMP instruction permanently changes the program counter. A CALL instruction leaves
information on the stack so that the original program execution sequence can be resumed.
10. What is the difference between the shift and rotate instructions?
A rotate instruction is a closed loop instruction. That is, the data moved out at one end is
put back in at the other end. The shift instruction loses the data that is moved out of the last bit
locations.
11. What is meant by Wait State?
This state is used by slow peripheral devices. The peripheral devices can transfer the data
to or from the microprocessor by using READY input line. The microprocessor remains in wait
state as long as READY line is low. During the wait state, the contents of the address,
address/data and control buses are held constant.
12. List the four instructions which control the interrupt structure of the 8085
microprocessor.
• DI (Disable Interrupts)
• EI (Enable Interrupts)
• RIM (Read Interrupt Masks)
• SIM (Set Interrupt Masks)
13. What is the signal classification of 8085?
All the signals of 8085 can be classified into 6 groups
• Address bus
• Data bus
• Control and status signals
• Power supply and frequency signals
• Externally initiated signals
• Serial I/O ports
14. What are operations performed on data in 8085
The various operations performed are
• Store 8-bit data
• Perform arithmetic and logical operations
• Test for conditions
• Sequence the execution of instructions
• Store data temporarily during execution in the defined R/W memory locations called the
Stack
15. Steps involved to fetch a byte in 8085
i. The PC places the 16-bit memory address on the address bus
ii. The control unit sends the control signal RD to enable the memory chip
iii. The byte from the memory location is placed on the data bus
iv. The byte is placed in the instruction decoder of the microprocessor and the task is
carried out according to the instruction
16. What are the interrupts of 8085 ?
The 8085 has 5 interrupt signals; they are INTR, RST7.5, RST6.5, RST5.5 and TRAP
17. What is an instruction?
An instruction is a binary pattern entered through an input device to command the
microprocessor to perform that specific function
18. What is the use of ALE
The ALE is used to latch the lower order address so that it can be available in T2 and T3
and used for identifying the memory address. During T1 the ALE goes high, the latch is
transparent ie, the output changes according to the input data, so the output of the latch is the
lower order address. When ALE goes low the lower order address is latched until the next ALE.
19. Explain the signals HOLD, READY and SID
HOLD indicates that a peripheral such as DMA controller is requesting the use of address
bus, data bus and control bus. READY is used to delay the microprocessor read or write cycles
until a slow responding peripheral is ready to send or accept data. SID is used to accept serial
data bit by bit
20. What is the use of addressing modes, mention the different types
The various formats of specifying the operands are called addressing modes, it is used to
access the operands or data. The different types are as follows
• Immediate addressing
• Register addressing
• Direct addressing
• Indirect addressing
• Implicit addressing
UNIT II 8086 S
A microprocessor is a multipurpose, programmable logic device that reads binary
instructions from a storage device called memory accepts binary data as input and processes data
according to those instructions and provides result as output. The power supply of 8085 is +5V
and clock frequency in 3MHz.
2. List few applications of microprocessor-based system.
It is used:
i. For measurements, display and control of current, voltage,
temperature, pressure, etc.
ii. For traffic control and industrial tool control.
iii. For speed control of machines.
3. What are the functions of an accumulator?
The accumulator is the register associated with the ALU operations and sometimes I/O
operations. It is an integral part of ALU. It holds one of data to be processed by ALU. It also
temporarily stores the result of the operation performed by the ALU.
4. List the 16 – bit registers of 8085 microprocessor.
Stack pointer (SP) and Program counter (PC).
5. List the allowed register pairs of 8085.
• B-C register pair
• D-E register pair
• H-L register pair
6. Mention the purpose of SID and SOD lines
SID (Serial input data line):
It is an input line through which the microprocessor accepts serial data.
SOD (Serial output data line):
It is an output line through which the microprocessor sends output serial data.
7. What is the function of IO/M signal in the 8085?
It is a status signal. It is used to differentiate between memory locations and I/O
operations.When this signal is low (IO/M = 0) it denotes the memory related operations. When
this signal is high (IO/M = 1) it denotes an I/O operation.
8. List out the five categories of the 8085 instructions. Give examples of the instructions
for each group.
• Data transfer group – MOV, MVI, LXI.
• Arithmetic group – ADD, SUB, INR.
• Logical group –ANA, XRA, CMP.
• Branch group – JMP, JNZ, CALL.
• Stack I/O and Machine control group – PUSH, POP, IN, HLT.
9. Explain the difference between a JMP instruction and CALL instruction.
A JMP instruction permanently changes the program counter. A CALL instruction leaves
information on the stack so that the original program execution sequence can be resumed.
10. What is the difference between the shift and rotate instructions?
A rotate instruction is a closed loop instruction. That is, the data moved out at one end is
put back in at the other end. The shift instruction loses the data that is moved out of the last bit
locations.
11. What is meant by Wait State?
This state is used by slow peripheral devices. The peripheral devices can transfer the data
to or from the microprocessor by using READY input line. The microprocessor remains in wait
state as long as READY line is low. During the wait state, the contents of the address,
address/data and control buses are held constant.
12. List the four instructions which control the interrupt structure of the 8085
microprocessor.
• DI (Disable Interrupts)
• EI (Enable Interrupts)
• RIM (Read Interrupt Masks)
• SIM (Set Interrupt Masks)
13. What is the signal classification of 8085?
All the signals of 8085 can be classified into 6 groups
• Address bus
• Data bus
• Control and status signals
• Power supply and frequency signals
• Externally initiated signals
• Serial I/O ports
14. What are operations performed on data in 8085
The various operations performed are
• Store 8-bit data
• Perform arithmetic and logical operations
• Test for conditions
• Sequence the execution of instructions
• Store data temporarily during execution in the defined R/W memory locations called the
Stack
15. Steps involved to fetch a byte in 8085
i. The PC places the 16-bit memory address on the address bus
ii. The control unit sends the control signal RD to enable the memory chip
iii. The byte from the memory location is placed on the data bus
iv. The byte is placed in the instruction decoder of the microprocessor and the task is
carried out according to the instruction
16. What are the interrupts of 8085 ?
The 8085 has 5 interrupt signals; they are INTR, RST7.5, RST6.5, RST5.5 and TRAP
17. What is an instruction?
An instruction is a binary pattern entered through an input device to command the
microprocessor to perform that specific function
18. What is the use of ALE
The ALE is used to latch the lower order address so that it can be available in T2 and T3
and used for identifying the memory address. During T1 the ALE goes high, the latch is
transparent ie, the output changes according to the input data, so the output of the latch is the
lower order address. When ALE goes low the lower order address is latched until the next ALE.
19. Explain the signals HOLD, READY and SID
HOLD indicates that a peripheral such as DMA controller is requesting the use of address
bus, data bus and control bus. READY is used to delay the microprocessor read or write cycles
until a slow responding peripheral is ready to send or accept data. SID is used to accept serial
data bit by bit
20. What is the use of addressing modes, mention the different types
The various formats of specifying the operands are called addressing modes, it is used to
access the operands or data. The different types are as follows
• Immediate addressing
• Register addressing
• Direct addressing
• Indirect addressing
• Implicit addressing
UNIT II 8086 S