Software Flashcards
Software
code that runs on the hardware
Boot/reboot
- when computer is first powered on, it runs a tiny “powered on” program
- this program looks for a disk containing an OS to run
Operating System
- a supervisory program that runs the administration behind the scenes
- gives each program its own area of memory and window, attempting to limit what an erroneous or malicious program can do
Sandboxing
mediating the access of each program so it operates indepedently, without interfering with other pgorams or the system as a whiole
Program
- when you double click a program to run it, the block of bytes of instructions for the program are copied into the RAM, and then the CPU is directed to begin running at the first instruction in that area of RAM
- “fetch/execute” cycle = CPU gets the first instruction in the sequence, executes it, then fetches the next instruction, executes it, and so on
- millions of simple “machine code” (aka “native code”) instructions
- loops and if statements involved
Firefox is 80 MB in size. Assuming all those bytes are instructions, and each instruction is 4 bytes, how many machine code instructions make up Firefox?
80 MB is 80 million bytes, so that would be 20 million instructions
The CPU in the computer directly “runs” a sequence of what type of instruction?
Machine Code
After a CPU runs an instruction, what does it most often do next?
runs the next instruction in the sequence of instructions
Suppose you double click Firefox.exe on a computer to run it. What best describes what happens?
The operating system copies the instructions for Firefox from disk to RAM and then the CPU runs the instructions in the RAM