There are many parts to a modern computer, most of them critical in some way or another. One of the core parts is memory. Without memory, a computer wouldn’t be able to store any data. Several computer components fit the basic description of “memory,” but the term generally only refers to system RAM.
An SSD uses solid-state flash memory to store data permanently. This data can persist without requiring an active power source. An HDD has the same purpose as an HDD but uses magnetic fields to store data on spinning platters. HDDs are much slower than SSDs because of their moving parts. Other data storage media such as USB thumb drives, DVDs, CDs, or floppy disks could all be classed as memory devices. To minimize confusion, however, between long-term storage devices such as these, and system RAM, these devices tend to be referred to as “storage” rather than “memory.”
Memory is used to store data for the currently running processes. Holding this data in memory is important as it allows the CPU to access it in a much shorter timeframe than it would if it needed to go to storage. Where possible, the RAM is not queried. The CPU is aware of its upcoming instructions and tries to preload the specific parts of memory it will need into the CPU cache memory. This cache is much faster still than the RAM but has a much lower capacity. Sometimes it isn’t possible to have the data ready in the cache, so the request goes to RAM.
History of Computer Memory
The first type of digital RAM used in computers was the Williams Tube, invented in 1946. It consisted of a cathode ray tube beaming a pattern onto a screen. A magnetic sensor would read the electrostatic field coming off the screen at close range and feed that back to refresh the screen as needed. While a few other technologies were developed, none were commercialized until magnetic core memory in 1955. Core memory encoded data in the magnetic fields of a set of magnetic cores and wires. Magnetic core memory remained in use until it was superseded in the early 1970s.
Technology at this point had advanced to allow small DRAM chips. These were placed directly on the motherboard in DIP packages in early use. This meant that a memory upgrade required the replacement of a large number of DRAM chips. It also took up a lot of space on the motherboard. Eventually, memory chips were moved to a secondary board called a SIMM. The DIMM later replaced this.
Both the SIMM and DIMM are small daughterboards that stick up perpendicular to the motherboard. They contain DRAM chips. The difference is in connectivity. SIMMs essentially have one set of pins. DIMMs have electrically different connectors on either side of the daughterboard providing double the pin count at minimal extra cost, size or complexity.
These DRAM chips have changed a lot over the years, going from asynchronous to being synchronized with a clock. They also operate at a double data rate, transferring data on both the rising and falling edge of the clock signal. Standards are still evolving to increase speeds though current standards have reached the limit of what is currently possible to manufacture in terms of transfer speed and latency.
Necessity of Memory
Theoretically, it would be possible to make a computer that doesn’t have any RAM. Such a computer, however, would run horrendously slowly, as any cache miss, if such a cache were in place, would have to go to the much slower storage drive. The start-up sequence of a computer is programmed to check that memory is present. Computers will refuse to boot up without any memory installed.
Windows 11 requires at let 4GB of RAM installed to launch. If you try to use the minimum amount of memory, you won’t have a good time. The operating system requires RAM, as do all running programs. When running such a low amount of RAM, you’re likely to run into many performance or stability issues when your RAM capacity is reached, even when not running many programs. Generally, it is recommended to have at least 8GB of RAM in a modern computer. More than this is overkill for standard home and office tasks but may be necessary for specific workloads such as gaming, video editing, and audio editing.
In computing, the term memory tends to refer to system RAM specifically. Other memory devices, such as SSDs and HDDs, may sometimes be referred to as memory devices but are typically distinguished as “storage” rather than “memory”. The CPU cache, likewise, tends to be referred to as “cache” or “cache memory.” Memory is used to store the data relating to the currently running programs.
Modern computers have memory physically located on DIMMs that plug into specific slots on the motherboard. At least 4GB of memory is quired for Windows 11 to run. Generally, more memory is better for performance. Once you’ve got more than you need for your workload, more becomes unnecessary. As such, it’s essential to balance the amount of memory in your computer with the budget and the amount of memory required by your current and potential future workloads when building a computer.