Answer Key i Cycle1 Ec 1301 MPMC
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SHANMUGANATHAN ENGINEERING COLLEGE ARASAMPATTI – 622 507 CYCLE TEST I – ANSWER KEY Branch : EEE Sub Code : EC1301 Year/ Sem : III/VI Sub Title : Microprocessor & Microcontroller Time : 10.00 am – 12.00 pm Max .Marks: 50 Date : 02.02.12 Key prepared by: N.Venkatakrishnan PART - A 1. What is the use of an ALE signal? Address Latch Enable signal is used to demultiplexing the lower order address and data line in the 8085 microprocessor. During first T state, this signal is raised to logic hi gh for getting lower order address. 2. Explain HLDA & HOLD signal. HOLD (Input) HOLD; indicates that another Master is requesting the use of the Address and Data Buses. Upon receiving the Hold request, The CPU will relinquish the use of buses as soon as the completion of the current machine cycle. Internal processing can continue. The processor can regain the buses only after the Hold is removed. When the Hold is acknowledged, the Address, Data, RD-, WR-, and IO/M- lines are 3stated. HLDA (Output) HOLD ACKNOWLEDGE; indicates that the CPU has received the Hold request and that it will relinquish the buses in the next clock cycle. HLDA goes low after the Hold request is removed. The CPU takes the buses one half clock cycle after HLDA goes low. 3. Differentiate Memory mapped IO and IO mapped IO. Memory mapped IO o 65536 address locations can be assigned for IO devices o MEMR/ MEWR signals are to perform data transfer IO Mapped IO o 256 IO devices address can be assigned o IOR/IOW signals are used to perform data transfer o 4. Draw the Flag register bit format. 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), and Auxiliary Carry (AC) flags; their bit positions in the flag register are shown in the Figure below. The most commonly used flags are Zero, Carry, and Sign. The microprocessor uses these flags to test data conditions.
Transcript of Answer Key i Cycle1 Ec 1301 MPMC
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SHANMUGANATHAN ENGINEERING COLLEGE
ARASAMPATTI – 622 507
CYCLE TEST I –
ANSWER KEY
Branch : EEE Sub Code : EC1301
Year/ Sem : III/VI Sub Title : Microprocessor & Microcontroller
Time : 10.00 am – 12.00 pm Max .Marks: 50
Date : 02.02.12 Key prepared by: N.Venkatakrishnan
PART - A
1. What is the use of an ALE signal?
Address Latch Enable signal is used to demultiplexing the lower order address and
data line in the 8085 microprocessor. During first T state, this signal is raised to logic high for
getting lower order address.
2. Explain HLDA & HOLD signal.
HOLD (Input) HOLD; indicates that another Master is requesting the use of the Address and Data
Buses. Upon receiving the Hold request, The CPU will relinquish the use of buses as soon as
the completion of the current machine cycle. Internal processing can continue. The processor
can regain the buses only after the Hold is removed. When the Hold is acknowledged, theAddress, Data, RD-, WR-, and IO/M- lines are 3stated.
HLDA (Output) HOLD ACKNOWLEDGE; indicates that the CPU has received the Hold request and
that it will relinquish the buses in the next clock cycle. HLDA goes low after the Hold request
is removed. The CPU takes the buses one half clock cycle after HLDA goes low.
3. Differentiate Memory mapped IO and IO mapped IO.
Memory mapped IO
o 65536 address locations can be assigned for IO deviceso MEMR/ MEWR signals are to perform data transfer
IO Mapped IO
o 256 IO devices address can be assigned
o IOR/IOW signals are used to perform data transfer
o 4. Draw the Flag register bit format.
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), and Auxiliary Carry (AC) flags; their bit positions
in the flag register are shown in the Figure below. The most commonly used flags are Zero,
Carry, and Sign. The microprocessor uses these flags to test data conditions.
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5. Write an ALP to perform 10 counting operation with a help of B register.
MVI B,0Ah
MVI A,01
L1: ADD A
DCR B
JNZ l1
6. What is the significance of SIM & RIM instruction?
RIM is a multipurpose instruction used to read the status of interrupts 7.5, 6.5, 5.5 and
to read serial input data bit. RIM loads 8-bit data in the accumulator to Read the interruptmask (bit 2, 1, 0), Identify pending interrupts (bit 6, 5, 4) and Receive serial input data bit (bit
7).
SIM is a multipurpose interrupt used to implement the 8085 interrupts (RST 7.5, 6.5,
5.5) and serial data output. SIM interprets the accumulator content as follows:
1 Mask the interrupts (bit 2, 1, 0).
2 To Reset RST 7.5 (bit 4). This is mainly used to overwrite RST 7.5 without serving it.
3 To implement serial I/O (bit 7, 6). If bit 6 = 1 is used to enable serial I/O and bit 7 is used to
transmit serial output data bit.
7. List the Various addressing modes of 8085 microprocessor
Immediate addressing, Register addressing, direct addressing, indirect addressing,implicit addressing
PART - B
Answer all the questions (4x9=36)
1. Explain the architecture of 8085 microprocessor with neat sketch.
Architecture diagram 4 marks
Explanation 5 marks2. Explain the instruction set of 8085 microprocessor with an example.
Data Transfer Group, Arithmetic Logical Group 3 Marks
Branch Group, Stack I/O, and Machine Control Instructions 3 marks
Example 3 Marks
3. Explain the interrupt driving mechanism of 8085 microprocessor.
Diagram 4 Marks
Explanation 5 Marks
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4. Write an assembly language program to perform 8 bit BCD addition
Program 6 Marks
Sample data 3 Marks
MVI C,00LXIH 8200
MOV A,M
INX H
ADD M
DAA
JNC L1
INR C
L1: INX H
MOV M,A
INX H
MOV M,C
HLT
