CS1 week 5 flashcards (MARIE, CPU, Memory...)
What is the main role of cpu
driving force of fetch, decode, execute instructions (cycle)
What are the 2 principle parts of the cpu
. The datapath
.The control unit
What does the datapath consist of
It consists of the ALU and registers which are connected to each other and to memory by data bus
What are registers
specialised forms of memory that has specific data stored inside it
Why are registers fast?
They are close in proximity to cpu
What does the control unit do
send signals to activate various components
to perform sequenced operations
.ensure instructions are fetched, decoded and executed in correct sequence
How is computer memory ordered
A linear array of addressable storage cells
What is a word
A storage cell of memory of fixed size
what does word addressable mean
cpu identifies specific storage cells (words) to read and write data to and from memory
what does it mean by byte addressable
cpu identifies data by bytes -smaller parts (usually half) of a word- eg if a word is 16 bits processor may identify particular 8 bits of memory rather than the word
How many memory locations is 4M X 16 Ram chips
4 x 2^20 16 bit memory locations
. M - 2^20
. 16 part of 4Mx 16 tells you no of bits
What are the 2 ways io devices can be connected 2 cpu through interfaces
. Memory mapped
.Instruction mapped
What does it mean by memory mapped
There is a reserved section of memory for input and output devices through which CPU interacts
What does it mean by instruction mapped
CPU has specific instructions for controlling i/o devices
what is a bus
An array of wires that simultaneously transmit a single bit along each line