IT 105 QUIZ 2 QUESTIONS & ANSWERS
Buses that interconnect high-speed I/O devices with the computer must support
___________________________-- - Answer -high data transfer rate
Why are I/O interfaces necessary? - Answer -Different formats required by the devices
Incompatibilities in speed between the devices and the CPU that make synchronization
difficult
Bursts of data vs. streaming data
Device control requirements that would tie up too much CPU time
Method for transferring data between main memory and a device that bypasses the
CPU - Answer -Direct Memory access controllers
Programmed I/O - Answer -A style of I/O programming where the CPU, running the
device driver, performs the copying of all data between the I/O device controller and
main memory.
Programmed I/O - Answer -CPU controlled
Interrupt Driven I/O - Answer -External input controls
In Programmed I/O the CPU is involved in every I/O transaction, whereas in Direct
Memory Access the CPU has no involvement
True of False - Answer -True
Primary user of Programmed I/O - Answer -Keyboard
Signal that causes the CPU to alter its normal flow of instruction execution - Answer -
interrupts
Examples of interrupts - Answer -Unexpected input
Abnormal situation
Illegal instructions
Multitasking, multiprocessing
One or more special control lines to the CPU - Answer -Interrupt Lines (Hardaway)
Program that services the interrupt
Also known as an interrupt routine or device driver - Answer -Interrupt handlers
, Saved registers of a program before control is transferred to the interrupt handler -
Answer -Context
Allows program to resume exactly where it left off when control returns to interrupted
program - Answer -Context
Notify that an external event has occurred
-Real-time or time-sensitive
Signal completion
-Printer ready or buffer full
Allocate CPU time
-Time sharing
Indicate abnormal event (CPU originates for notification and recovery)
-Illegal operation, hardware error
Software interrupts - Answer -Use of Interrupts
Define the diagram - Answer -Interrupt Cycle
Address of interrupting device is included in the interrupt
Requires additional hardware to implement - Answer -Vectored Interrupt
Once the interrupt occurs, the system must determine which device, of all the devices
associated with a given interrupt, issued the interrupted. Identifies interrupting device by
polling each device. General interrupt is shared by all devices - Answer -Polling
Transferring large blocks of data
Direct transfer to and from memory - Answer -Direct Memory Access(DMA)
Required conditions for DMA - Answer --the I/O interface and memory must be
connected
-the I/O controller must be capable of reading and writing to memory
-conflicts between the CPU and the I/O controller must be avoided
-interrupt required for completion
Privileged instructions can only be executed by the operating system kernel or a
privileged process, that require direct access to hardware or other privileged resources,
such as setting up memory mappings, accessing I/O devices, etc. - Answer -Privileged
programmed I/O instructions
To initiate DMA, programmed I/O is used to send the following information: - Answer -1.
Location of data on I/O device
2. Starting location in memory
3. Size of the block
4. Direction of transfer: read or write
What does the DMA do after completing its task? - Answer -Interrupt the CPU
Buses that interconnect high-speed I/O devices with the computer must support
___________________________-- - Answer -high data transfer rate
Why are I/O interfaces necessary? - Answer -Different formats required by the devices
Incompatibilities in speed between the devices and the CPU that make synchronization
difficult
Bursts of data vs. streaming data
Device control requirements that would tie up too much CPU time
Method for transferring data between main memory and a device that bypasses the
CPU - Answer -Direct Memory access controllers
Programmed I/O - Answer -A style of I/O programming where the CPU, running the
device driver, performs the copying of all data between the I/O device controller and
main memory.
Programmed I/O - Answer -CPU controlled
Interrupt Driven I/O - Answer -External input controls
In Programmed I/O the CPU is involved in every I/O transaction, whereas in Direct
Memory Access the CPU has no involvement
True of False - Answer -True
Primary user of Programmed I/O - Answer -Keyboard
Signal that causes the CPU to alter its normal flow of instruction execution - Answer -
interrupts
Examples of interrupts - Answer -Unexpected input
Abnormal situation
Illegal instructions
Multitasking, multiprocessing
One or more special control lines to the CPU - Answer -Interrupt Lines (Hardaway)
Program that services the interrupt
Also known as an interrupt routine or device driver - Answer -Interrupt handlers
, Saved registers of a program before control is transferred to the interrupt handler -
Answer -Context
Allows program to resume exactly where it left off when control returns to interrupted
program - Answer -Context
Notify that an external event has occurred
-Real-time or time-sensitive
Signal completion
-Printer ready or buffer full
Allocate CPU time
-Time sharing
Indicate abnormal event (CPU originates for notification and recovery)
-Illegal operation, hardware error
Software interrupts - Answer -Use of Interrupts
Define the diagram - Answer -Interrupt Cycle
Address of interrupting device is included in the interrupt
Requires additional hardware to implement - Answer -Vectored Interrupt
Once the interrupt occurs, the system must determine which device, of all the devices
associated with a given interrupt, issued the interrupted. Identifies interrupting device by
polling each device. General interrupt is shared by all devices - Answer -Polling
Transferring large blocks of data
Direct transfer to and from memory - Answer -Direct Memory Access(DMA)
Required conditions for DMA - Answer --the I/O interface and memory must be
connected
-the I/O controller must be capable of reading and writing to memory
-conflicts between the CPU and the I/O controller must be avoided
-interrupt required for completion
Privileged instructions can only be executed by the operating system kernel or a
privileged process, that require direct access to hardware or other privileged resources,
such as setting up memory mappings, accessing I/O devices, etc. - Answer -Privileged
programmed I/O instructions
To initiate DMA, programmed I/O is used to send the following information: - Answer -1.
Location of data on I/O device
2. Starting location in memory
3. Size of the block
4. Direction of transfer: read or write
What does the DMA do after completing its task? - Answer -Interrupt the CPU
