Grade 11 Text Book LU 3 Flashcards
(33 cards)
What is the start-up and boot sequence of a computer?
When a computer is switched on, and before the operating system is loaded, the hardware devices that will be used by the computer need to be checked. Once they are deemed to be correct, the operating system which resides on the main hard drive of the computer will be loaded in RAM together with the drivers for the hardware devices. A boot sequence is this initial set of operations that the computer performs when it is switched on.
What is a boot loader?
The program that performs the boot sequence which ends with the entire operating system being loaded is known as the boot loader (or bootstrap loader).
What is BIOS?
BIOS is short for Basic Input-Output System. It is low-level software that resides in a non-volatile ROM chip on a computer’s motherboard.
What is firmware?
Software that permanently resides on ROM is known as firmware.
What is BIOS responsible for?
The BIOS is responsible for the POST, or Power-On Self-Test and loading the operating system. When the computer turns on the following process is followed:
* The BIOS begins the Power-On Self-Test to check the hardware.
* An inventory of the hardware connected to the computer is obtained from the CMOS (Complementary Metal-Oxide-Semiconductor).
* The hardware is tested to determine if it is functioning correctly.
* The BIOS locates the Master Boot Record (MBR), a section of code usually stored on the hard disk drive. The MBR is responsible for loading and executing the operating system kernel, which continues with the start-up procedure.
What is a Kernel?
The kernel is the core of a computer’s operating system that remains in RAM. It is responsible for input/output requests from software, translating them into instructions for the CPU. It handles memory and peripherals like keyboards, monitors, printers, and speakers.
What is CMOS?
CMOS is a battery-backed, volatile memory that stores:
* hardware settings - the types of hardware installed on your computer such as the disk drive.
* user settings - the current date and time.
What is CMOS responsible for in the boot up process?
To obtain data about the system.
What is UEFI?
Unified Extended Firmware Interface (UEFI). Not all hardware supports UEFI but UEFI can emulate BIOS so it can boot old Operating Systems. Backwards compatible
Advantages of UEFI over BIOS
- The UEFI firmware can boot from drives of 2.2 TB or larger.
- UEFI can run in 32-bit or 64-bit mode which has more address space than BIOS; this means that the boot process is faster.
- UEFI setup screens can be more user-friendly than BIOS settings screens, including graphics and mouse cursor support. BIOS doesn’t have the capability of using mouse and graphics drivers.
UEFI features that BIOS doesn’t have?
- It supports Secure Boot, which means the operating system can be checked for validity to ensure no malware has tampered with the boot process.
- It can support networking features right in the UEFI firmware itself, which can aid in remote troubleshooting and configuration, which is not possible with a traditional BIOS.
- It’s not just a BIOS replacement either - UEFI is essentially a tiny operating system that runs on top of a computer’s firmware, and it can do a lot more than a BIOS.
- It may be stored in flash memory on the motherboard or it may be loaded from a hard drive or network share at boot.
What is a interrupt?
An interrupt is a signal sent to the CPU from hardware or software indicating the need for the CPU’s attention. Can be generated by software or hardware.
What is an example of a software interrupt
Dividing by zero, square rooting a negative number or when an Input / Output (I/O) is required. It can also occur when the timer indicates that a process has had its allocated amount of CPU cycles.
What is an example of a hardware interrupt
An example of a hardware interrupt is when a signal is sent from a device, such as the keyboard indicating that a key has been pressed, or a printer indicating that it has run out of paper.
What will a device do if there are multiple interrupt requests?
When the device has multiple interrupt outputs to handle, it will handle them in the order of their relative priority.
What is a IRQ?
Every device has a unique Interrupt Request Number (IRQ) which the CPU uses to identify which device is interrupting it. For example, the Keyboard has IRQ 1
What is a IO Range?
An IO Range is a buffer, a temporary storage area in RAM, used to speed up a slow input/output device.
What is an example of an IO Range?
Reading a file in programming: when you read from a text file, instead of reading line by line, will take many CPU cycles just for one line. It is much more efficient to load the entire file into a buffer in memory so as not to violate the very important rule that the CPU is never idle. When you write to a file, instead of writing line by line, the entire file is written to a buffer, and when the close file command is called, the file is saved to secondary storage and the buffer is flushed (cleared) for the next similar processing request.
What is processing techniques?
Processing techniques, used by software and hardware, are designed to optimise the efficiency of a computer system.
What is Multitasking?
With multitasking, there are several programs stored in the computer’s RAM and the CPU switches very short bursts of processing time between all the running programs so that the user seems to be running several programs simultaneously. Multiple tasks on a single processor.
What is process scheduling?
Involves giving each running process its fair share of the CPU’s time without letting any process remain suspended for too long.
How does a computer allow multitasking to work?
- A process occupies a certain amount of RAM. It also makes use of registers within the CPU and operating-system memory space.
- When two processes are multi-tasking, the operating system allots a certain number of CPU execution cycles to one program.
- After that number of cycles, the operating system makes copies of all the registers used by the processes and notes the point at which the process paused in its execution.
- It then loads all the registers used by the second process and allows it a certain number of CPU cycles.
- When those are complete, it makes copies of all the registers used by the second program and loads the first program.
What is multithreading?
One program can have several different threads (parts of a program that run independently) running at the same time. This is called multithreading.
What is Virtual Memory?
When RAM is full the operating system can use a section of the hard disk as an extension of RAM.
This virtual memory extends the number of addresses that RAM has and requires pages to be swapped between RAM and the hard disk. This is the opposite of caching.
