for finals Flashcards

1
Q

What are the functions of computers?

A
  1. Data processing
    - wide data variety that requires a broader processing
  2. Data storage - long & short term
  3. Data movement
    -I/O = data to/from peripherals connection
    - data communication = data from long distance via remote devices.
  4. control - control unit manages computer’s resources & response to instructions
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2
Q

What is the function of Control Unit?

A
  • controls CPU/ computer operation
  • response to/ execute instructions
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3
Q

What is the function of ALU?

A

Performs data processing functions.

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4
Q

What are the structural components of the computer?

A
  1. CPU - controls computer operation & performs data processing
  2. I/O - data transfer between computers and external devices
  3. Main memory - to store data
  4. System Interconnection - provides communication of data between computer components
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5
Q

What is direct access?

A
  • involves a shared read & write mechanism
  • individual blocks has unique address based on physical location
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6
Q

What is sequential access?

A
  • memory is an organized data unit called records
  • accessed is in a specific linear sequence
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7
Q

What is random access

A
  • each memory address has a unique addressing mechanism
  • location is randomly selected & directly accessed.
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8
Q

What is memory hierarchy?

A
  • separates computer memory in hierarchy based on response time
  • lower access time, higher cost per bits
  • greater capacities, lower cost per bits & greater access time
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9
Q

What are the types of addressing modes?

A
  1. immediate
  2. Direct & indirect
  3. Register
  4. Register indirect
  5. Displacement
  6. Stack
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10
Q

What is immediate addressing mode?

A
  • data is presented in instruction address
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11
Q

What is direct & indirect addressing mode?

A
  • direct = operand’s offset is in the instruction as 8-bit/16-bit displacement element

-indirect = contains the effective address of memory location where the actual data consists.

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12
Q

What is register & register indirect addressing mode?

A
  • register = operands contained in a register set

register indirect = addressing operands are placed in one of the registers eg, BI,BX,SI,DI

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13
Q

What is displacement (auto indexed) addressing mode?

A
  • effective address of operands in register content
  • increment = register content is increment after accessing operands
  • decrement = register content is decrement before accessing operands
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14
Q

What is stack addressing mode?

A
  • operands at the top of the stack
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15
Q

What is EPROM?

A
  • erasing process = repeatedly (UV)
  • cost = expensive than PROM
  • update capabilities = multiple
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16
Q

What is EEPROM?

A
  • erasing process = electrically
  • cost = most expensive than EPROM
  • write operation = written without erasing prior contents
17
Q

What is Flash Memory?

A
  • functionalities = between EPROM & EEPROM
  • cost = between EPROM & EEPROM
  • erasing process = single action due to organized microchips.
18
Q

What is RAID & how many levels are there?

A
  • Redundant Assembly of Independent Disk
  • level 0 -6 (7)
19
Q

What is RAID 0?

A
  • no redundancy
  • 2 requirements of high transfer rate
    1. high transfer capacities = stays on the path between host device & disk drive
    2. I/O request = application to drive disk array effectively
  • I/O request is the I/O time dominated by seek & latency time
20
Q

What is RAID 1?

A
  • redundancy via mirroring
  • data striping by mapping all the data to 2 separate physical disk with 1 being the mirror disk
  • no write penalty
  • costly due to double storage
21
Q

What is RAID 2?

A
  • redundancy via Hamming code
  • parallel access
  • synchronization of spindles & same head position
  • data striping can be as small as a word or byte
  • Hamming error correcting code to correct single-bit error & detect double-bit error
22
Q

What is RAID 3?

A
  • redundancy via bit-interleaved parity
  • like RAID 2, synchronization of spindles & same head position
  • parallel access, all disks are access at once
  • data striping into bits and stored into parity disk
  • reduced mode is required to be reconstructed for data retrieval
23
Q

What is RAID 4?

A

-redundancy via block-level parity
- independent access, each disk operates independently
- calculate new parity needs to read old user strip & old parity strip
- write penalty = new write requires array management software to update both user strip with the corresponding parity bits

24
Q

What is RAID 5?

A

-redundancy via block-level distributed parity
- organized similar to RAID 4
- parity strips are distributed across all disk
- allocation is round-robin scheme
- takes 2 disks fail for data loss

25
Q

What is RAID 6?

A
  • redundancy via dual-redundancy
  • 2 different parity strips are stored on 2 different disks & blocks
  • high data availability & recover
  • takes 3 disks for data loss
  • substantial write penalty, 2 parity disk affected.
26
Q

What are the types of I/O commands?

A
  1. Control = activate peripherals & tells what to do
  2. Test = test status condition associated with I/O modules & peripherals
  3. Read = I/O module obtain data from peripheral & place it in internal buffer
  4. Write = I/o module obtain data from data bus & transmit to peripheral
27
Q

What are the key interface of OS?

A
  1. Instruction Set Architecture (ISA)
  2. Application Binary Interface (ABI)
  3. Application Program Interface (API)
28
Q

What is ISA?

A
  • boundary between software & hardware
  • allows software to control CPU via machine language
29
Q

What is ABI?

A
  • in between OS and application in the context of binary codes
  • defines the system call interface to the OS & hardware resources & services of the system via user ISA
30
Q

What is API?

A
  • gives programs access to hardware resources
  • application software to be ported easily to other system with the same API
31
Q

What are the services provided by the OS?

A
  1. Program creation & execution
  2. access I/O devices
  3. Error detection & responses
  4. Accounting
  5. System access
32
Q

What are the scheduling of multiprogramming?

A
  1. Long-term = Add into the pool of processes to be executed
  2. Medium-term = Add a number of processes either partially/fully into the main memory (swapping in & out)
  3. Short-term = available processes will be executed by the processor
    = makes fine-grained decision on what to execute next
33
Q

What is I/O scheduling?

A
  • any pending I/O request can be handled by any available I/O device
34
Q

What is Virtual memory demanding paging?

A
  • each page of a process is brought in when needed
  • principle of locality
    1. subroutine = large process execution may be confined in a small section of a program
  1. page fault = if page is not within main memory, OS will fetch the desired page

pros 1. more processes maintain in memory
2. time saving by swapping in & out

cons
1. page replacement (1 page in1 page out)
2. OS has to fetch page again before the page used is thrown out

35
Q

What is Virtual Memory Address Translation?

A
  1. Supersections = 16Mb blocks of MM
  2. Sections = 1Mb blocks of MM
  3. Large pages = 64kb blocks of MM
  4. Small pages = 4kb blocks of MM

Lvl 1 table
- holds descriptors containing base address & translation properties for Supersections & Sections
- pointers to lvl 2 tables

Lvl 2 table
- holds descriptors containing base address & translation properties for Large & Small pages