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WorksheetsProgrammable I/O Port 8255
Total questions: 46
Worksheet time: 23mins
Programmable peripheral input-output port is another name for
serial input-output port
parallel input-output port
serial input port
parallel output port
Port C of 8255 can function independently as
input port
output port
either input or output ports
both input and output ports
All the functions of the ports of 8255 are achieved by programming the bits of an internal register called
data bus control
read logic control
control word register
none of the mentioned
The data bus buffer is controlled by
control word register
read/write control logic
data bus
none of the mentioned
The input provided by the microprocessor to the read/write control logic of 8255 is
RESET
A1
WR(ACTIVE LOW)
All of the mentioned
The device that receives or transmits data upon the execution of input or output instructions by the microprocessor is
control word register
read/write control logic
3-state bidirectional buffer
none of the mentioned
The port that is used for the generation of handshake lines in mode 1 or mode 2 is
port A
port B
port C Lower
port C Upper
If A1=0, A0=1 then the input read cycle is performed from
port A to data bus
port B to data bus
port C to data bus
CWR to data bus
The pin that clears the control word register of 8255 when enabled is
CLEAR
SET
RESET
CLK
In the I/O mode, the 8255 ports work as
reset pins
set pins
programmable I/O ports
only output ports
In BSR mode, only port C can be used to
set individual ports
reset individual ports
set and reset individual ports
programmable I/O ports
The feature of mode 0 is
any port can be used as input or output
output ports are latched
maximum of 4 ports are available
all of the mentioned
The strobed input/output mode is another name of
mode 0
mode 1
mode 2
none
If the value of the pin STB (Strobe Input) falls to low level, then
input port is loaded into input latches
input port is loaded into output latches
output port is loaded into input latches
output port is loaded into output latches
The pulse width of the signal INIT at the receiving terminal must be more than
10 microseconds
20 microseconds
40 microseconds
50 microseconds
The signals that are provided to maintain proper data flow and synchronization between the data transmitter and receiver are
handshaking signals
control signals
input signals
none
The feature of mode 2 of 8255 is
single 8-bit port is available
both inputs and outputs are latched
port C is used for generating handshake signals
all of the mentioned
The device that enables the microprocessor to read data from the external devices is
printer
joystick
display
reader
The example of output device is
CRT display
7-segment display
Printer
All of the mentioned
The input and output operations are respectively similar to the operations,
read, read
write, write
read, write
write, read
The operation, IOWR (active low) performs
write operation on input data
write operation on output data
read operation on input data
read operation on output data
The latch or IC 74LS373 acts as
good input port
bad input port
good output port
bad output port
While performing read operation, one must take care that much current should not be
sourced from data lines
sinked from data lines
sourced or sinked from data lines
sinked from address lines
To avoid loading during read operation, the device used is
latch
flipflop
buffer
tristate buffer
What must be the contents of the control word of Intel 8255 for Mode 0 (operation) and for the following ports configuration : Port A-output, Port B-output, Port Clower-Output, Port Cupper-input
85 H
86 H
87 H
88 H
Ports are used to connect the CPU to which of the following units? 1. Printer 2. Floppy disk drives 3. Video display unit 4. Incoming power supply Select the correct answer using the codes given below
1 and 2
2 and 3
3 and 4
1 and 3
When the 82C55 is reset, its I/O ports are all initializes as
output port using mode 0
Input port using mode 1
output port using mode 1
Input port using mode 0
Which pins are general purpose I/O pins during mode-2 operation of the 82C55?
PA0 - PA7
PB0-PB7
PC3-PC7
PC0-PC2
Which is the commonly used programmable interface and particularly used to provide handshaking:
8251
8254
8259
8255
Which provide a mechanism to establish a link between the microprocessor and i/o device
Input interface
Output interface
Both a and b
None of these
In which the processor uses a protection of the memory address to represent I/O ports
Memory mapped I/O
I/O memory mapped
Both a and b
None of these
The standard I /O is also called
I/O mapped I/O
Isolated I/O
Both a and b
None of these
The processor of knowing the status of device and transferring the data with matching speeds is called
Handshaking
Peripheral
Ports
None of these
Which is designed to automatically manage the handshake operation?
8251
8254
8255
8259
Which mode is used for single handshake in 8255?
Mode 0
Mode 1
Mode 2
None of these
Which mode is used for double handshake in 8255?
Mode 0
Mode 1
Mode 2
None of these
Which mode is used for simple input or output without handshaking?
Mode 0
Mode 1
Mode 2
None of these
Which PORT C pins are used for port B in 8255 mode 1?
PC0-PC2
PC3-PC7
PC6-PC7
PC3-PC5
Which are used for port A in 8255 mode 1?
PC0-PC2
PC3-PC7
PC6-PC7
PC3-PC5
Which are used for handshake lines for port A in 8255 mode 2?
PC0-PC2
PC3-PC7
PC6-PC7
PC3-PC5
A handshake signal in a data transfer is transmitted
Along with the data bits
Before the data transfer
After the data transfer
Either along with the bits or after the data transfer
How many ports do 8255 have?
3
4
5
6
How many modes do 8255 have?
3
4
5
6
Which of the following mode of 8255 is Strobed Bi-directional I/O?
Mode 0
Mode 1
Mode 2
Mode 4
Which of the following port can be programmed nibble wise (separately)?
Port A
Port B
Port C
Port D
Port A and UPPER nibble of Port C come under ----- Group.
A
B
C
None
