1. Define microprocessor?
A microprocessor is a multipurpose, programmable,
clock-driven, register –based electronic device that reads binary instructions from a storage device called memory .
Accepts binary data as input and processes data
according to instructions, and provides result as output.
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2. Explain
the
function of ALE
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in the 8085
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architecture?
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(or) How address
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and data lines
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are
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demultiplexed?
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The ALE
signal goes high
at the
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beginning of
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each machine
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cycle indicating the
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availability
of
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the
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address on the address bus,
and the signal is used to latch the low-order address bus(A0-A7) by
demultiplexing the address/data bus(AD0-AD7),which
are multiplexed.
3. What is the function of HOLD and HLDA?
HOLD- It indicates when another device is
requesting the use of address and
data bus(like DMA controller).
HLDA(Hold Acknowledge)- It indicates that HOLD request has been received. After
the removal of HOLD request the HLDA goes low.
4. What is the purpose of READY and TRAP pins in 8085 Microprocessor?
READY- It is used to interface slow speed peripherals with microprocessor. TRAP- Vectored and
non-maskable hardware interrupt.
5. List the operations performed by IO/M in 8085.
Memory Read, Memory Write ,I/O Read, I/O Write are the operations
performed by IO/M in 8085.
6. Differentiate between Memory mapped I/O and I/O mapped I/O.
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S.NO
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Memory mapped I/O
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I/O mapped I/O
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1.
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It is treated as memory location
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It is not treated
as memory location
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2.
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No special instructions are needed to access
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It
requires special instructions like IN,
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the I/O devices
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OUT to
access I/O devices
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3.
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Microprocessor can
access 1 MByte
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Microprocessor
can access 64 KByte
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memory locations or I/O ports
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memory locations or I/O ports
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4.
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It requires 20 address lines
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It requires 16 address lines
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5.
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MEMR,
MEMW signals can
be used to
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IOR , IOW signals are used
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access I/O
devices
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6.
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It is suitable for small system
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It is suitable for large system
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7.
If
a 6Mhz crystal is connected with 8085, how much
is the time taken by 8085 to complete
opcode fetch cycle and memory read cycle?
Clock frequency = crystal frequency
/
2 = 6 Mhz/2
=3Mhz One T-state = 1/ clock
freq
=1/(3Χ106)
= 0.333μsec
Time for opcode fetch cycle = 4 Χμs 0.33= 1.332 μsec Time for memory read cycle= 43Χ 0.33=0.999 μsec
8. Write the operation carried out when 8085 executes DAD rp instruction and which flag is affected?
DAD- means DOUBLE ADDITION. It is used to perform
addition of two 16 bit data.
[HL]= [HL]+ [rp]
The contents
of rp pair
is added with the HL content and the result is stored in HL pair register. On execution of this
instruction only carry flag (CY) is affected
9. What are the flags available in 8085?
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S
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Z
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AC
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P
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CY
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S- sign flag Z-Zero flag
AC- Auxiliary carry flag
P-Parity flag
CY- Carry flag
10. Specify the five control signals commonly used by the 8085 MPU.
1. RD-Read signal 2.WR-
Write signal 3.READY- Ready signal
4.ALE- Address Latch Enable 5.CLK OUT –Clock Out Signal
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