Quiz 1 - pt. 1 Flashcards
Operating System:
A program that acts as an intermediary between a user of a computer and the computer hardware.
OS goals:
- execute use programs and make solving user problems easier.
- make the computer system convenient to use.
- use the computer hardware in an efficient manner.
Four components of a computer system:
- computer hardware
- operating system
- system and app programs
- users?
user view VS system view
user view:
- ease of use
- doesn’t care of utilization
system view:
- maximize utilization
- protect system from malicious/non-malicious users
kernel:
- resource allocator
- needs to work all the time
- initial code loaded at boot
describe kernel mode:
kernel mode, as opposed to user mode, is where the system starts when it boots up. It’s where instructions are privileged, meaning they are only executable in kernel mode, and where the Operating System has unrestricted access.
byte:
8 bits
word:
depends on architecture:
4-bit words, 8-bit, 16-bit, 32-bit, etc.
nibble:
4-bits
Kilobyte (KB):
1024 bytes
2^10 bytes
Megabyte(MB):
2^20 bytes
Gigabyte(GB):
2^30 bytes
Terabyte(TB):
2^40 bytes
Petabyte(PB):
2^50 bytes
Exabyte :
2^60 bytes
Zettabyte :
2^70 bytes
bootstrap program:
loaded at power-up or reboot:
- typically stored in ROM or EPROM, generally known as firmware
- initializes all aspects of system
- loads OS kernel and starts execution
Computer-system organization:
computer-system operation:
- one or more CPUs, device controllers connect through common bus providing access to shared memory
- concurrent execution of CPUs and devices competing for memory cycles
Device controller informs CPU that it has finished its operation by causing a(n):
interrupt!
The typical computer system organization has shared memory, device controllers, and one/more CPUs connected through a common communication channel called a(n):
bus!
The disk controller notices the CPU that it has fetched the data by issuing a(n):
interrupt!
interrupt:
transfers control to the interrupt service routing generally, through the , which contains the addresses of all the service routines
interrupt architecture must save:
the address of the interrupted instruction
incoming interrupts are disabled while another interrupt is being processed to prevent:
a lost interrupt!
trap:
a software-generated interrupt caused either by an error or a user request
An operating system is ____ driven.
interrupt driven!
Describe DMA:
Direct Memory Access:
- when a device transfers a block of data to/from its own buffer to memory without the help of the CPU
(used for high-speed I/O devices to transmit info at close to memory speeds)
caching:
information in use copied from slower to faster storage temporarily.
cache size and replacement policy:
when cache is full, an algorithm must choose which items to discard to make room for new ones.
swapping:
if processes don’t fit in memory, swapping moves them in and out to run.
(part of Timesharing (multitasking) concept)
