Seminar 2 Flashcards
Systems Architeture and Processor Technology
what is a computer processor
device that performs data manipulation
can conduct computing (+, -, x)
comparision (>, =)
data movement between storage and I/O outlets
how are complex tasks / program accomplished (describe it)
- instructions are commands to the processor to perform a specific function.
- each instruction is simple, and when a computer is “running an instruction” it is executing it.
- complex instructions are accomplished by combining instructions into a program and executing them.
General Purpose Processor vs Specific Purpose Processor
GPP: has instruction program stored in the storage system. information in the storage can be altered, thus changing the program instruction and function executed by processor.
SPP: has a single program “wired” into the storage. info in storage cannot be altered.
what do computers need to store?
- Intermediate processing results
- Data
- Programs
different characteristics of storage devices
- speed
- volatility
- cost per bit
?? ? HDD > SSD > NVME
what are the 4 major functions of Computer Hardware?
- Internal communication (system bus)
- external communication (wifi)
- processing
- storage
what is a CPU
General purpose processor that executes instructions. they are implemented on microprocessor chips, each chip has multiple processors.
4 main components of computer system
- CPU: a processor that conducts comparison, computation and data movement.
- Main Memory: stores data and instructions
- System bus: communication channel for all components in computer system.
- I/O devices: External communication
CPU components
- CU: Moves data to registers and other storage systems. performs operations if its data movement, but if it is computation or logic, then it directs ALU to execute it.
- Registers: stores data. holds input and output from ALU
- ALU (Arithmetic Logic Unit): performs computation and logic operations.
properties of secondary storage
- cheaper than pri storage per bit
- non-volatile (can hold data indefinitely)
- slower than main mem (RAM)
- hold large quantities of data
System Bus
- communication channel that links all the devices in the computer system.
- huge factor for affecting the speed of the computer system.
draw a diagram showing the important parts of computer system
refer to slide 15 sem 2 of parker notes
CPU components and functions
CPU is brain of the computer system. It executes all program instruction. In cpu, there is Control Unit (CU), that directs all computer system actions, such as processing, storage, I/O and data movement.
***Describe Fetch and Execution cycle
Fetch:
the CU reads instruction stored in Main Memory.
CU increments the PC or the instruction pointer. and then instruction is decoded.
CU stores instruction in the Instruction Register (IR)
if there is data embedded in the instruction, it is stored in data registers as inputs to the ALU.
If there is memory addresses in the instruction, they are copied from the memory and stored in registers as inputs to the ALU.
Execute:
ALU retrieves the instruction and data from the reigsters.
comparision and computation instructions are executed by the ALU, in response to a signal in the CU.
final result stored in the instruction register (AC, Accumulator).
What is instruction and what are its components?
instruction is a sequence of bits that must be decoded to extract the processing function or data input or address of data inputs.
OP Code: unique binary code representing the processing function, and template fro extracting the operands.
Operands: one or two groups of bits after the OP code, containing data to be processed or identify the location of that data (register or memory address)
clock rate
cycle time = 1 / clock rate (GHz) (billions of ticks per second)
Different types of registers
General Purpose Registers:
- stores transient data
- law of diminishing value graph.
- every ALU has a dozen registers.
Special Purpose Registers:
- AC (Accumulator) stores the calculations given by the ALU
- PC (Program Counter) stores memory address of next instruction to be fetched (Instruction Pointer)
- Instruction Register contains copy of the most recent instruction that has been fetched.
- PSW (Program Status Word) is a set of bit flags that contains errors, such as (0 division)
**word size equation
memory location = memory size / word size
RAM has 4 bits. WS = 1.
Per memory location, there is 4 bits.
1 2 3 4
⬜⬜⬜⬜
1 ⬜
2 ⬜
3 ⬜
4 ⬜
(1 goes to 1, 2 goes to 2, …)
(vertical is the address, horizontal is the RAM)
Techniques to speed up computer
- Memory Caching
*2. Pipelining
*3. Multiprocessing
*4. Branch Prediction
Multiprocessing
multiple ALUs, Multiple CPUs
- Operating systems are more complex because they now manage more
processing resources and more complex application software - Application software that takes advantage of multiprocessing is more complex because it must be designed for parallel execution (a.k.a. multithreading)
Pipelining Technique
- Fetch from memory
- Increment and store program counter (PC)
- Decode instruction and store operands and instruction pointer
- Access ALU inputs
- Execute instruction within the ALU
- Store ALU output
Pipelining attempts to overlap instruction execution by performing each stage on a different instruction at the same time.
Complexities of Pipelining:
1. is one ALU enough?
2. is one PC enough?
3. is one IR enough?
4. What happens if a branch is encountered?
if it is not branched, use the prefetched instruction. if it is branched, discard the pre fetched instruction and fetch new instruction. Multiprocessing used to handle branching issues.
