ITEC 274 - Final Exam questions n
answers graded A+ passed
Peripheral - correct answer ✔✔devices are input / output / storage communication devices that
connect to the computer's primary computing devices of the processor and main memory (can
be internal or external)
Device management - correct answer ✔✔involves overseeing the delicate balance of the
system's finite supply of devices with the user's almost infinite demand for them
The four basic functions of Device Management - correct answer ✔✔1. Monitoring the status of
each device
2. Enforcing present policies to determine which process gets device and for how long
3. Allocating each device
4. Deallocating each device
bit manipulators - correct answer ✔✔Computers are digital data processors used to turn data
into information.
Computers use at least 3 ways to represent bits - correct answer ✔✔Magnetic, Optical, or
Electricity
Magnetic - correct answer ✔✔+ - charge
Optical - correct answer ✔✔absence or presence of reflective light
Electricity (voltage) - correct answer ✔✔solid state
,From the OS perspective there are three device types - correct answer ✔✔Dedicated, Shared,
and Virtual
Dedicated device - correct answer ✔✔Assigned to one job at a time:
- for entire time that job is active (or until released)
- EX. tape drivers, printers, and plotters
Disadvantage:
- must be allocated for duration of job execution - inefficient if device not used 100 percent of
time
Shared device - correct answer ✔✔Assigned to several processes.
- EX. direct access storage device (DASD)
Virtual device - correct answer ✔✔Dedicated and shared device combination - dedicated device
transformed into shared device
EX. printer
- converted by spooling program
Spooling - correct answer ✔✔speeds up slow dedicated I/O device
OS Device Manager divides I/O task into 3 parts - correct answer ✔✔I/O traffic controller,
scheduler, and handler
I/O traffic controller - correct answer ✔✔- Watches status of devices, control units, channels
- Three main tasks:
, 1. Determine if path available
2. If more than one path available, determine which one to select
3. If paths all busy, determine when one is available
- Maintains database containing each unit's status and connections
I/O schedular - correct answer ✔✔- Similar job as process scheduler
- Allocates devices, control units, and channels
- If requests greater than available paths (decides which request to satisfy first: based on
different criteria)
I/O device handler - correct answer ✔✔- Performs actual data transfer
1. Processes device interrupts
2. Handles error conditions
3. Provides detailed scheduling algorithms
- Device dependent
Storage devices are classified by several factors - correct answer ✔✔Type of medium: magnetic,
optical, solid state
Access Method: sequential, direct
Capacity: how much can be stored (# bytes)
Access Time: how fast can save \ retrieve data
etc (fixed \ removable).
answers graded A+ passed
Peripheral - correct answer ✔✔devices are input / output / storage communication devices that
connect to the computer's primary computing devices of the processor and main memory (can
be internal or external)
Device management - correct answer ✔✔involves overseeing the delicate balance of the
system's finite supply of devices with the user's almost infinite demand for them
The four basic functions of Device Management - correct answer ✔✔1. Monitoring the status of
each device
2. Enforcing present policies to determine which process gets device and for how long
3. Allocating each device
4. Deallocating each device
bit manipulators - correct answer ✔✔Computers are digital data processors used to turn data
into information.
Computers use at least 3 ways to represent bits - correct answer ✔✔Magnetic, Optical, or
Electricity
Magnetic - correct answer ✔✔+ - charge
Optical - correct answer ✔✔absence or presence of reflective light
Electricity (voltage) - correct answer ✔✔solid state
,From the OS perspective there are three device types - correct answer ✔✔Dedicated, Shared,
and Virtual
Dedicated device - correct answer ✔✔Assigned to one job at a time:
- for entire time that job is active (or until released)
- EX. tape drivers, printers, and plotters
Disadvantage:
- must be allocated for duration of job execution - inefficient if device not used 100 percent of
time
Shared device - correct answer ✔✔Assigned to several processes.
- EX. direct access storage device (DASD)
Virtual device - correct answer ✔✔Dedicated and shared device combination - dedicated device
transformed into shared device
EX. printer
- converted by spooling program
Spooling - correct answer ✔✔speeds up slow dedicated I/O device
OS Device Manager divides I/O task into 3 parts - correct answer ✔✔I/O traffic controller,
scheduler, and handler
I/O traffic controller - correct answer ✔✔- Watches status of devices, control units, channels
- Three main tasks:
, 1. Determine if path available
2. If more than one path available, determine which one to select
3. If paths all busy, determine when one is available
- Maintains database containing each unit's status and connections
I/O schedular - correct answer ✔✔- Similar job as process scheduler
- Allocates devices, control units, and channels
- If requests greater than available paths (decides which request to satisfy first: based on
different criteria)
I/O device handler - correct answer ✔✔- Performs actual data transfer
1. Processes device interrupts
2. Handles error conditions
3. Provides detailed scheduling algorithms
- Device dependent
Storage devices are classified by several factors - correct answer ✔✔Type of medium: magnetic,
optical, solid state
Access Method: sequential, direct
Capacity: how much can be stored (# bytes)
Access Time: how fast can save \ retrieve data
etc (fixed \ removable).
