What Is RAM?

RAM, or random-access memory, is the memory a computer uses as its workspace. When you start a program, the processor copies it from storage into RAM, along with the data it is working on, because RAM can be read and written thousands of times faster than even a fast SSD.

“Random access” means any location can be reached directly in the same short time, rather than by working through the data in order as a tape does. RAM is measured in gigabytes, and in almost every modern computer it is built from DRAM chips on a memory module or soldered to the board.

Think of the processor as working at a desk. Its cache is what it holds in its hands, RAM is the desk itself, and storage is the filing cabinet across the room. The bigger the desk, the more programs and data can be open at once without a trip to the cabinet.

When RAM runs out, the operating system moves the least-used data out to a page file or swap space on the SSD. That keeps the system running, but every access to that data is now far slower, which is why a computer short of RAM feels sluggish rather than simply stopping. The difference between memory and storage comes down to this split: RAM is fast and temporary, storage is slower and permanent.

Several kinds of memory share the RAM name. The ones you meet when choosing a computer are these.

ROM, or read-only memory, is the other half of a common comparison. ROM keeps its contents without power and holds the code a device needs before anything else runs. In modern computers the “ROM” is usually a flash chip that can be updated, holding the UEFI firmware, so the line between the two is about role, not just technology.

RAM is the classic example of volatile memory, and ROM of non-volatile memory, which is why a computer can always boot after a power cut but loses any unsaved work.

The right amount depends on the operating system and the workload, not on the size of the computer. As a rough guide for current systems:

Beyond the amount, three questions shape the choice. First, is the memory upgradeable? Boards with DIMM or SO-DIMM slots can be expanded later, while soldered LPDDR is fixed at the time of order but resists shock and vibration better. Second, does the application need ECC? Third, will the modules be available for the life of the project? Industrial modules with a fixed bill of materials and a wide temperature rating avoid surprises on repeat orders.

Our industrial motherboards range from boards with soldered memory to server boards with ECC DIMM slots, so the memory can be matched to the workload rather than the other way round.

We fit the memory in every system we supply as standard, matching capacity, ECC, module type and temperature rating to the workload, then validate the build before it ships.