Flashcards
4: Logic Gates and Logic Circuits
Cards in this deck (18)
- 1Logic PropositionA statement that is either TRUE or FALSE
- 2Problem StatmentAn informal definition of an outcome which is dependent on one logic proosition or a combination of two or more logic propositions.
- 3Logic ExpressionLogic propositions combined using Boolean operations which may be equated to a defined outcome.
- 4Boolean operatorsAND
OR
NOT
XOR
NAND
NOR - 5Logic GateA component of a logic circuit that has an operation matching that of a Boolean operator.
- 6Give truth table and symbol of NOT gate
- 7Give truth table and symbol of AND gate
- 8Give truth table and symbol of OR gate
- 9Give truth table and symbol of XOR gate
- 10Give truth table and symbol of NAND gate
- 11Give truth table and symbol of NOR gate
- 12Fill in : RAM and ROM are both examples of ____ memory. One item that is stored in RAM is ____ One item stored in ROM is ____ RAM can either be SRAM or DRAM. SRAM uses transistors arranged as ____ DRAM uses tranisstors and ___primary
software running
boot-strap program
flip-flops
capacitors - 13explain difference between PROM, EPROM and EEPROM 3 PROM can be set once, EPROM and EEPROM can be overwritten
multiple times.
EPROM needs to be removed from device EEPROM can be erased in
situ.
EPROM and can be erased using UV light, EEPROM can be erased
using voltage // is flash storage .
EPROM must be entirely erased before rewriting, EEPROM does not
have to be entirely erased before rewriting. - 14Describe principal operations of a magnetic hard drive 5 The hard disk has (one or more) platter/plate/disk
Each surface of the platter/disk is (ferrous oxide which is) capable of
being magnetised
The platters/disks are mounted on a (central) spindle
The entire mechanism is contained inside a sealed (aluminium) box.
The disks are rotated (at high-speed)
(Each surface of the disk) has a read/write head mounted on an arm
(positioned just above the surface)
Electronic circuits control the movement of the arm (and hence the
heads)
The surface of the platter/disk is divided into concentric tracks / circles
The surface of the platter/disk is divided into sectors
One track in one sector is the basic unit of storage called a block
The data is encoded as a magnetic pattern for each block
When writing to disk, a variation in the current in the head produces a
variation in magnetic field on the disk
When reading from disk, a variation in magnetic field produces a
variation in current through the head - 15Describe advantages of using a relational database compared to a file-base approach 4 Reduced data redundancy // less repeated data
...because each item of data is only stored once
Maintains data consistency // improves data integrity
...changes in one table will automatically update in another
... linked data cannot be entered differently in two tables
Program-data independence
...changes to the data do not require programs to be re-written
Complex queries are easier to run
Can provide different views
....so users can only see specific aspects of the database - 16Describe the role of the registers in the F-E cycle 5The Program Counter (PC) holds the address of the next instruction ...
...and the contents are incremented / changed to the next address each
cycle
The Memory Address Register (MAR) holds the address to fetch the data
(from the PC)
The Memory Data Register (MDR) holds the data at the address in MAR
The instruction is transferred to Current Instruction Register (CIR) for
decoding and execution - 17Describe when interrups are detected in the F-E cycle and how the interrupts are handled 5At the start/end of a FE cycle
Priority is checked
If lower priority than current process continue with F-E cycle
If higher priority than current process ...
... state of current process is / registers are stored on stack
Location / type of interrupt identified...
...appropriate ISR is called to handle the interrupt
When ISR finished, check for further interrupts (of high priority) / return to
step 1
Otherwise load data from stack and continue with process - 18What are the facotrs that can affect the performance of the computer and how do they impact hte performance? 4 Clock speed...
...higher clock speed means more FE cycles per second
Number of cores...
...means more instructions can be carried out simultaneously
Bus width ...
...allows the transfer of more data each time // allows more memory
locations to be directly accessed
Cache ...
... the higher capacity the more frequently used instructions it can store
for fast access
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- A Level AS Computer Science (Unit 1: Theory Fundamentals) Flashcards on 4: Logic Gates and Logic Circuits, created by HRYN red on 31/12/2022.
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- HRYN red
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