OS And Runtime Basics Flashcards
When should you use the heap instead of the stack?
if you don’t know exactly how much data you will need at run time or if you need to allocate a lot of data.
memory hierarchy
a concept in which computers have a few megabytes of very fast, expensive, volatile cache memory, a few gigabytes of medium-speed, medium-priced, volatile main memory, and a few terabytes of slow, cheap, nonvolatile magnetic or solid-state disk storage, not to mention removable storage, such as DBDs and USB sticks
memory manager
the part of the operating. system that manages (part of) the memory hierarchy
ROM stands for
Read-Only Memory
RAM stands for
Random Access Memory
BIOS stands for
Basic Input Output System
What was the danger of in early operating system memory models having the OS be stored in RAM?
a bug in the user program can wipe out the operating system, possibly with disastrous result
What memory model is used in some handheld computers and embedded systems?
device drivers at top of memory in a ROM, and the and the rest of the system in RAM down below
Buffer
data buffer (or just buffer) is simply a region of a physical memory storage used to temporarily store data while it is being moved from one place to another. Typically, the data is stored in a buffer as it is retrieved from an input device (such as a microphone) or just before it is sent to an output device (such as speakers). However, a buffer may be used when moving data between processes within a computer. A majority of buffers are implemented in software
Round Robin
a CPU scheduling algorithm where each process is assigned a fixed time slot in a cyclic way. It is simple, easy to implement, and starvation-free as all processes get fair share of CPU. … It is preemptive as processes are assigned CPU only for a fixed slice of time at most.
