COS 122 S01 Terminology

Basic hardware components…

CPU, Main Memory, I/O modules, System Bus

Processor/CPU

Controls the operation of a computer, loading and executing instructions

Main Memory

Volatile memory, storing data and programs

I/O Modules

Moves data between the computer between its external components

System Bus

Communication line among processors, main memory, and I/O modules

PC

Program Counter. Address of the next instruction to be fetched

IR

Instruction Register. Holds the instructions concurrently being executed

MAR

Memory Address Register. Specifies the address in memory for the next read/write

MBR

Memory Buffer Register. Contains the data to be written to, or the data read from memory

I/O AR/BR

Input/Output address/buffer registers

What are the design constraints of memory

Capacity, Speed, Price

What are the trade offs of memory

Faster access time = greater cost per bit. Greater capacity = smaller cost per bit. Greater capacity = slower access time.

Memory Hierarchy

Decreasing cost per bit - Increasing capacity - Increasing access time - Decreasing frequency of access

Cache Memory

Small, fast, memory between the CPU and main memory, to exploit locality of reference and reduce effective memory access time

Operating system

A program that controls the execution of application programs / An interface between application and hardware

Major advantages of OS development

Multiple user processes, Memory management, Security, Job scheduling, Resource management

Fault Tolerance

The ability of a system or component to continue operation despite the presence of faults

PCB

Process Control Block. Contains all the information about a process needed by the OS (read and/or modified by nearly all modules of the OS)

Name and describe all of the Process Model States

New: A process has been created but not yet placed in the pool of executable processes

Ready: Processes that are prepared to run if given the opportunity

Running: Process that is currently being executed

Blocked: A process that cannot be executed until a specific event has occurred

(

Ready/Suspended: The process is still in primary memory and is not waiting on an event

Blocked/Suspended: The process has been moved to secondary memory and is waiting on an event

)

Exit: A process that has been released by the OS

User Mode Execution

Less privileged mode. User programs typically execute in this mode

Kernel Mode

More privileged mode. Kernel of the operating system executes in this mode

Thread

Unit of dispatching

Process

Unit of resource ownership

Multithreading

The ability of an OS to support multiple, concurrent paths of execution within a single process

Benefits to threads

Quicker to create, terminate, and switch between threads in the same process and enhanced efficiency of communications between programs

ULT

User Level Threads. Thread management is managed by the application, and the kernel is not aware of the existence of threads.

KLT

Kernel Level Threads. Thread management is done by the kernel. Only an API to the kernel thread facility.

Amdahl Lore

Calculates the speed up that will occur when a certain number of processors (N), the inherently serial (1-f) and infinitely paralleziable information of the system is taken into account.