Microprocessors Questions and Answers – Modes of Operation of 8255

This set of Microprocessor Multiple Choice Questions & Answers (MCQs) focuses on “Modes of Operation of 8255”.

1. In the I/O mode, the 8255 ports work as
a) reset pins
b) set pins
c) programmable I/O ports
d) only output ports
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2. In BSR mode, only port C can be used to
a) set individual ports
b) reset individual ports
c) set and reset individual ports
d) programmable I/O ports
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3. The feature of mode 0 is
a) any port can be used as input or output
b) output ports are latched
c) maximum of 4 ports are available
d) all of the mentioned
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4. The strobed input/output mode is another name of
a) mode 0
b) mode 1
c) mode 2
d) none
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5. If the value of the pin STB (Strobe Input) falls to low level, then
a) input port is loaded into input latches
b) input port is loaded into output latches
c) output port is loaded into input latches
d) output port is loaded into output latches
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6. The signal, SLCT in the direction of signal flow, OUT, indicates the selection of
a) Control word register
b) CPU
c) Printer
d) Ports
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7. The pulse width of the signal INIT at the receiving terminal must be more than
a) 10 microseconds
b) 20 microseconds
c) 40 microseconds
d) 50 microseconds
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8. The level of the signal ERROR(active low) becomes ‘low’ when the printer is in
a) Paper end state
b) Offline state
c) Error state
d) All of the mentioned
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9. The signals that are provided to maintain proper data flow and synchronization between the data transmitter and receiver are
a) handshaking signals
b) control signals
c) input signals
d) none
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10. The feature of mode 2 of 8255 is
a) single 8-bit port is available
b) both inputs and outputs are latched
c) port C is used for generating handshake signals
d) all of the mentioned
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