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PART – B (5 x 16 =80)

1. Explain with a help of neat diagram of Pin out details of 8085 microprocessor.

Intel 8085 consists of 40 pins and signal can be classified as follow:

Address Bus.

Data Bus.

Control and Status signals.

Power supply and frequency signals.

Externally initiated signals.

Serial I/O ports.

ADDRESS BUS

The 8085 has eight signal lines, A15 – A8 : Unidirectional, known as ‘high order

address’.

DATA BUS

AD7 – AD0: bidirectional and dual purpose (address and data placed once at a time).

AD7 – AD0 also known as ‘low order addresses’.

To execute an instruction, at early stage AD7 – AD0 uses as address bus and alternately

as data bus for the next cycle.

The method to be change from address bus to data bus known as ‘bus multiplexing’.

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CONTROL AND STATUS SIGNAL

ALE – This signal helps to capture the lower order address presented on the multiplexed

address/data bus.

The ALE (Address Latch Enable) signal enables the lower order address to be latched

externally.

RD – Read (active low). To indicate that the I/O or memory selected is to be read and

data are available on the bus.

WR – Write: Active low. This is to indicate that the data available on the bus are to be

written to memory or I/O ports.

IO/M – To differentiate I/O operation of memory operations.

‘0’ - indicates a memory operation.

‘1’-indicates an I/O operation.

IO/M combined with RD and WR to generate I/O and memory control signals.

S1 and S0: Status signals, similar to IO/M, can identify various operations as shown on

the following table :

S1 S2 Operations

0 0 HALT

0 1 WRITE

1 0 READ

1 1 FETCH

POWER SUPPLY AND FREQUENCY SIGNALS

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EXTERNALLY INITIATED SIGNALS

SERIAL I/O PORTS

SID (Input) – This is input signal is used to accept serial data bit by bit from the external

device.

SOD (Output) – This is an output signal which enables the transmission of serial data bit

by bit from the external device.

RESET SIGNALS

RESET IN: an active low input signal, Program Counter (PC) will be set to 0 and thus

MPU will reset.

RESET OUT: an output reset signal to indicate that the μp was reset (i.e. RESET IN=0).

It also used to reset external devices.

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2. Explain the architecture of 8085 with the required diagrams. Also write the salient

features of the same.

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3. Draw and explain about the 8085 timing diagram.

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4. (i) Write short notes on comparison between microprocessor & microcontroller.

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(ii) Classify and explain the Addressing modes of 8085.

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5. Draw and explain the architecture of 8051 microcontroller.

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6. Explain the classification of instruction set of the microprocessor 8085.

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7. Draw and explain the block diagram and operation of temperature controlling system

with a microprocessor.

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8. Draw and explain the block diagram and operation of Traffic light controller with a

microprocessor.

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9. Describe with neat diagram the stepper motor control using microprocessor.

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