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Computing topic 1 - CPU (Input, output and storage (Storage devices…
Computing topic 1 - CPU
Architecture
parts of the CPU
Control Unit - controls and monitors flow of data around CPU and between other components through controlling of buses. Also executes instructions.
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CIR - Hold the current instruction, which is split into operand and opcode
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FDE cycle
Fetch - contents of program counter sent to MAR
Contents of MAR sent to MDR and PC incremented by 1
Contents of MDR sent CIR
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execute - Instruction is carried and, results stored in ACC and/or main memory
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Input, output and storage
input devices - piece of hardware that is used to enter data into a comouter or a similar processing device e.g. smartphone
output device - piece of hardware that is used to output info from a computer or similar processing device
Storage devices
optical - very portable, very cheap, low cost/GB, low capacity, fairly portable, slow to write e.g. CD, DVD
magnetic - low cost/GB, high capacity, not portable as it has moving parts, therefore not robust, not as fast access speeds as flash e.g. HDD, magnetic tape
Flash - high RW speeds, fairly high capacity, high cost/GB, no moving parts so is robust and portable, less RW cycles than magnetic before it starts to slow down e.g. SSD, USB
RAM, ROM and
virtual storage
RAM - used as main memory, volatile memory, accessed directly by CPU at any time so can be run quickly
DRAM - used in RAM modules, less expensive than SRAM, slower read write speeds for CPU, needs a refresh signal to keep its data intact
SRAM - used in cache memory, more expensive than DRAM, faster read write speeds for CPU, no refresh signal required to keep the data intact
ROM - read only(can't write to it), non-volatile, on the motherboard, holds BIOS to boot up computer and check that everything in the computer is working properly, much smaller than RAM( few MB)
types of processor
CISC and RISC
CISC:Complex instruction set computing
Complex hardware, fewer registers
several clock cycles for some instructions
less programming code
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