7. OCR GCSE (J277) 1.2 RAM and ROM

Summary

This video delves into the roles of RAM and ROM in a computer system. ROM, soldered to the motherboard, contains the bootstrap instructions for initial hardware checks and loading the BIOS. It's non-volatile and holds firmware. RAM, on the other hand, is volatile and serves as temporary storage for the operating system and currently running programs. The video explains how ROM's bootstrap enables the CPU to recognize and load the operating system from the hard drive into RAM, initiating the boot process.

Takeaways

• 💾 **RAM and ROM are the two main types of primary storage in a computer system.**
• 🔩 **ROM is soldered to the motherboard and contains the initial instructions for the computer, known as the bootstrap.**
• 🛠️ **The bootstrap is used to check hardware installation and load the basic input-output system.**
• 📱 **Software on ROM is called firmware, and it can be updated by changing ROM chips in some systems.**
• 💿 **RAM serves as temporary storage for instructions and data for programs being executed by the processor.**
• 🖥️ **RAM holds the operating system when the computer is running, acting as a buffer between the CPU and the hard disk.**
• 🔌 **When a computer starts, it uses ROM to perform a power-on self-test (POST) to identify and initialize hardware components.**
• 🔄 **The POST process wakes up connected components and makes the CPU aware of their existence.**
• 🔧 **After POST, the computer uses ROM to load the operating system from the hard drive into RAM to start the boot process.**
• 🔑 **RAM is volatile and loses its contents when power is off, while ROM is non-volatile and retains data even when powered down.**
• 📊 **RAM is larger and used for active data and program storage, whereas ROM is smaller and stores essential startup instructions.**

Q & A

What are the two main types of memory in a computer system?

The two main types of memory in a computer system are RAM (Random Access Memory) and ROM (Read-Only Memory).

Where is ROM typically located in a computer system?

ROM is a small piece of memory soldered to the motherboard.

What is the purpose of ROM in a computer system?

ROM contains the very first instructions for the computer, such as checking hardware installation and loading the basic input-output system.

What is the term for the initial instructions stored on ROM?

The initial instructions stored on ROM are also known as the bootstrap.

What is the difference between software stored on ROM and other types of software?

Software stored on ROM is referred to as firmware, which is typically used in embedded systems.

Why is it necessary to have RAM in addition to long-term storage like a hard disk?

RAM is necessary because executing instructions directly from the hard disk would be too slow; instructions are transferred to RAM first for faster access.

What role does RAM play when a computer is running?

RAM holds the operating system, programs, and data in use by the CPU when the computer is running.

What is the purpose of the bootstrap stored in ROM during the computer startup process?

The bootstrap in ROM contains initial startup instructions that perform tasks such as a power-on self-test (POST), which helps the CPU to become aware of connected components like the hard drive.

How does the computer know to look for the operating system on the hard drive during startup?

The computer knows to look for the operating system on the hard drive during startup because of the bootstrap instructions in ROM, which perform a POST and make the CPU aware of the hard drive's existence.

What is the key difference between RAM and ROM?

RAM is volatile, holding the operating system and data in use by the CPU during operation, and is read/writeable and larger in size compared to ROM. ROM is non-volatile, holding the first startup instructions, is read-only, and is smaller in size compared to RAM.

Why is ROM described as non-volatile?

ROM is described as non-volatile because the contents remain even when the power is turned off.

Outlines

00:00

💾 Understanding RAM and ROM

This paragraph introduces the fundamental concepts of RAM and ROM in computer systems. The central processing unit (CPU) fetches instructions from memory, which is categorized into two main types: RAM (Random Access Memory) and ROM (Read-Only Memory). ROM is a small, non-volatile memory chip soldered to the motherboard that contains the bootstrap, the initial instructions for the computer to check hardware and load the basic input-output system (BIOS). This memory is also where firmware, software stored on ROM, resides. In contrast, RAM serves as a temporary storage for instructions and data for programs being executed by the processor. It is volatile, meaning data is lost when power is turned off, and it is larger than ROM. The video script explains the process of how a computer starts up, from the initial power-on self-test (POST) initiated by ROM to loading the operating system into RAM from the hard drive.

Keywords

💡Central Processing Unit (CPU)

The CPU, often referred to as the 'brain' of the computer, is responsible for executing instructions and processing data. In the context of the video, it is highlighted that the CPU fetches instructions from memory, emphasizing its role in the initial stages of a computer's operation. The CPU's function is crucial as it determines the computer's ability to perform tasks and process information.

💡Memory

Memory, in a computer system, refers to the hardware components that store data temporarily or permanently. The video script distinguishes between two primary types of memory: RAM and ROM. Memory is integral to the computer's operation as it allows for the storage and retrieval of data required for the CPU to function.

💡Random Access Memory (RAM)

RAM is a type of volatile memory that temporarily stores data and instructions for the CPU to execute. The video explains that RAM holds the operating system and data in use while the computer is running, and it is faster than accessing data from the hard disk. RAM's volatility means that its contents are lost when power is turned off, making it a critical component for the computer's immediate functioning.

💡Read-Only Memory (ROM)

ROM is a non-volatile memory that stores instructions and data permanently, even when the power is off. The video script mentions that ROM contains the bootstrap, which are the initial startup instructions used when a computer is first powered on. ROM's non-volatility ensures that essential system instructions are retained, allowing the computer to perform initial checks and load the operating system from the hard drive.

💡Bootstrap

The bootstrap refers to the initial set of instructions that a computer follows when it is powered on. As described in the video, these instructions are stored in ROM and are crucial for performing a power-on self-test and initializing the system. The term 'bootstrap' is used metaphorically to indicate that the computer 'pulls itself up' by loading these instructions to begin operation.

💡Firmware

Firmware is software that is embedded in hardware, typically stored in ROM. The video script explains that software stored on ROM is referred to as firmware, which includes the essential instructions for a computer's operation. Firmware is an example of how ROM is used to store and execute critical system software.

💡Power-on Self-Test (POST)

The POST is a diagnostic routine that runs when a computer is first turned on, as mentioned in the video script. It involves sending signals to all connected components, such as the hard drive, to ensure they are functioning correctly. The POST is a critical step in the computer's startup process, as it verifies the integrity of the hardware before the operating system is loaded.

💡Hard Drive

A hard drive is a non-volatile storage device that retains data even when the power is off. The video script describes how the operating system is typically stored on the hard drive but is too slow to be accessed directly by the CPU. Instead, it is loaded into RAM for faster access, highlighting the hard drive's role in long-term data storage.

💡Volatile

Volatile memory is a type of memory that loses its data when power is removed. The video script uses the term to describe RAM, emphasizing that its contents are temporary and require a constant power supply to be maintained. This characteristic of RAM is in contrast to ROM's non-volatile nature.

💡Non-volatile

Non-volatile memory retains data even when the power is turned off. The video script highlights ROM's non-volatile nature, which allows it to store the bootstrap and other critical instructions that the computer needs to start up. This feature is essential for the computer's ability to remember its initial setup and configuration.

Highlights

The central processing unit (CPU) fetches instructions from memory.

There are two main types of memory in a computer system: RAM and ROM.

ROM is a small piece of memory soldered to the motherboard.

ROM contains the first instructions for checking hardware and loading the basic input-output system.

The initial instructions in ROM are also known as the bootstrap.

Software stored on ROM is referred to as firmware.

ROM chips can be changed to update the program being executed, like in game cartridges.

RAM is a temporary storage for instructions and data for programs being executed by the processor.

RAM holds the operating system when the computer is running.

The CPU needs to load the operating system from the hard drive into RAM to function.

ROM contains the bootstrap to initiate the computer's startup process.

The POST (power-on self-test) is performed by the initial instructions in ROM.

The POST wakes up all connected components and makes the CPU aware of their existence.

RAM is volatile, meaning its contents are lost when power is turned off.

ROM is non-volatile, retaining its contents even when power is off.

RAM is read and writeable, and larger in comparison to ROM.

ROM is read-only and smaller in comparison to RAM.

Transcripts

- [Craig] The central processing unit fetches instructions from memory.

There are two main types of memory in a computer system, also known as primary storage.

In this video, we explore RAM and ROM.

(uplifting piano jingle)

The ROM is a small piece of memory soldered to the motherboard.

It contains the very first instructions for the computer,

to check the hardware is installed correctly and to load the basic input-output system.

These very first instructions are also known as the bootstrap.

Software stored on the ROM is referred to as firmware.

In some computer systems, ROM chips can be changed in order to change the program being executed.

An example of this are game cartridges in portable entertainment systems.

The RAM is a temporary storage of instructions and data for programs that are being executed by the processor.

Although the long-term storage is usually on the hard disk, it would be too slow to execute instructions from there.

Therefore, they are transferred from the disk to the memory first.

The RAM also holds the operating system when the computer is running.

Here, we see four important internal components of a computer system.

ROM, the CPU, RAM and a hard drive of some description.

When your computer very first turns on and receives power,

there are no instructions in the CPU.

What it needs to do is load the operating system so you can start using it.

Of course, the problem with this is that the operating system is stored on the hard drive

and at the moment your computer turns on, it doesn't even know the hard drive exists,

let alone that it should look there to find the operating system and load it into RAM.

The solution, as explained earlier, is ROM.

It contains the bootstrap, a set of initial startup instructions placed on it during manufacturing.

Now, this is slightly beyond the GCSE specification,

but these first initial instructions perform, amongst other tasks, a power-on self-test,

known as the POST,

which sends signals to all the other connected components such as the hard drive.

The POST, in very simple terms, wakes up all the connected components

and makes your CPU aware of their existence.

Now our computer is aware of the hard drive and the software stored on it,

it can go ahead and load these instructions into RAM and start the process of booting up your operating system.

So, let's just recap what we've learned.

Although both ROM and RAM contain instructions and data for the computer,

that is where the similarity ends.

The key difference is that RAM holds the operating system, programs and data

in use by the CPU when the computer is running.

It is volatile; the contents are lost when the power is turned off.

It's read and writeable, and it's large in comparison to ROM.

ROM holds the first instructions for when the computer is first turned on, known as the bootstrap.

Programs may be stored in ROM in embedded systems.

ROM is non-volatile; the contents remain when the power is turned off.

It is read-only and it is small in comparison to RAM.

(uplifting piano jingle)