for finals Flashcards
(35 cards)
1
Q
What are the functions of computers?
A
- Data processing
- wide data variety that requires a broader processing - Data storage - long & short term
- Data movement
-I/O = data to/from peripherals connection
- data communication = data from long distance via remote devices. - control - control unit manages computer’s resources & response to instructions
2
Q
What is the function of Control Unit?
A
- controls CPU/ computer operation
- response to/ execute instructions
3
Q
What is the function of ALU?
A
Performs data processing functions.
4
Q
What are the structural components of the computer?
A
- CPU - controls computer operation & performs data processing
- I/O - data transfer between computers and external devices
- Main memory - to store data
- System Interconnection - provides communication of data between computer components
5
Q
What is direct access?
A
- involves a shared read & write mechanism
- individual blocks has unique address based on physical location
6
Q
What is sequential access?
A
- memory is an organized data unit called records
- accessed is in a specific linear sequence
7
Q
What is random access
A
- each memory address has a unique addressing mechanism
- location is randomly selected & directly accessed.
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
9
Q
What are the types of addressing modes?
A
- immediate
- Direct & indirect
- Register
- Register indirect
- Displacement
- Stack
10
Q
What is immediate addressing mode?
A
- data is presented in instruction address
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.
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
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
14
Q
What is stack addressing mode?
A
- operands at the top of the stack
15
Q
What is EPROM?
A
- erasing process = repeatedly (UV)
- cost = expensive than PROM
- update capabilities = multiple
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
What is RAID 6?
- 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
What are the types of I/O commands?
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
What are the key interface of OS?
1. Instruction Set Architecture (ISA)
2. Application Binary Interface (ABI)
3. Application Program Interface (API)
28
What is ISA?
- boundary between software & hardware
- allows software to control CPU via machine language
29
What is ABI?
- 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
What is API?
- gives programs access to hardware resources
- application software to be ported easily to other system with the same API
31
What are the services provided by the OS?
1. Program creation & execution
2. access I/O devices
3. Error detection & responses
4. Accounting
5. System access
32
What are the scheduling of multiprogramming?
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
What is I/O scheduling?
- any pending I/O request can be handled by any available I/O device
34
What is Virtual memory demanding paging?
- 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
2. 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
What is Virtual Memory Address Translation?
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
