Primary Storage
Also known as primary memory. Once the data is input into a computer, it is stored in a place that can be accessed quickly by the computer’s processor. Primary storage is a computer’s internal storage and is in storage where data is held before processing. The capacity is small and separated into RAM and ROM. Both are memory chips.
Random Access Memory (RAM)
RAM holds data to be processed and data can be written and read from. Data and programs in RAM are held temporarily and erased when they are no longer needed. Content in RAM is only removed when computer’s power is switched off so it is ‘volatile’.
The amount of RAM in a computer varies on the computer. RAM can increase
the storage capacity and it will hold the operating systems. RAM is often built into peripherals such as printers. So when the printer prints the data, the computer can move onto other tasks.
Read Only Memory (ROM)
Four types of ROM
-Firmware – ROM that holds programs that run on an embedded computer. Firmware does not load if system fails.
-Bootstrap – ROM that contains startup instructions – PC/Laptop/Phone/tablet
-EPROM – Rewritable ROM – used in keyless systems and micro controllers
-Flashing – Upgrading firmware is known as flashing. ROM used on devices to recover OS/Firmware. Commonly used to erase/rewrite data to ROM
ROM is a primary storage that can be read but not written to. ROM does not lose its contents so it is ‘non-volatile’. The contents of ROM depends of the type of device. ROM tends to be smaller in capacity compared to RAM.
Certain types of ROM can be erased and re-written to. This is called the erasable programmable read only memory (EPROM). This is found when a device’s firmware needs to be upgraded.
–Embedded computers: computer that is built into a device that performs one or more specialized tasks such as a digital watch. Will have a few kilobytes of RAM, RAM will hold data for processing. It uses ROM to hold software that runs device such as amicrowave which can only complete specific functions. This is called firmware. The bios is inside the ROM which loads operating systems and tells if components are correct.
–General purpose computer: computer with many applications such as desktops PCs. Will have a few gigabytes of RAM, RAM holds operating system, running programs and data for processing.. It uses ROM to hold software known as bootstrap which contains start-up instructions for computers. Bootstrap determines the basic hardware structure of computer and instructions for loading the operating system
IGCSE COMPUTER SCIENCE 