Computer memory is abundant, cheap, and taken for granted. Years ago, what we know today as "computer storage" hardly existed. The story doesn't begin there, though. Computer memory, in one form or another, dates back to the dawn of computing itself. The Ancient Greek Antikythera mechanism, largely considered to be one of the first computers, employs seemingly simple yet mechanically complex memory. Millenia later, Charles Babbage, the 19th-century engineer and computer scientist, used another form of mechanical memory to create the first fully programmable mechanical computer.
To discover what qualifies as computer memory, a definition is in order. Almost all modern computers rely on the binary system. The term "binary" signifies two possible states - either a "0" or a "1." Computer memory relies on a system of recording and recalling the state of a specific value as either a zero or a one, known as a "bit." Bits can be strung together to create larger units of memory known as bytes, megabytes, gigabytes, and so forth.
At its physical core, a bit can be created in a few different ways. On computer hard disks, the zero or one is stored and recalled based on the magnetic orientation of a ferromagnetic disk. Random access memory (RAM) modules use solid state memory in the form of Boolean logic gates. Logic gates can be hydraulic, mechanical, electromechanical, optic, or most commonly, electronic devices, which generate a predictable output given a certain combination of inputs. When used together, logic gates can create evermore complex units of memory, with something called the SR flip-flop being one of the most simple. Then, of course, there are optical drives, such as CDs and DVDs that use microscopic pits on the surface of disks that can only be read by lasers.
In Babbage's day, bits were stored on punch cards fed into his mechanical computer. In fact, punch cards were invented before Babbage began experimenting with computers and remained in use for programming purposes until the mid-20th century.
The goal of all computer memory is to store as much data as possible in as little space as possible. Beyond that, several secondary requirements must be considered. For instance, computer "memory" and computer "storage" are not necessarily the same thing, and are used in two different ways (although computer storage is frequently used as an umbrella term to encompass both storage and memory). Computer memory is what computer engineers would call RAM, programmable read-only memory (PROM), erasable PROM (EPROM), electronically erasable PROM (EEPROM), etc. Memory needs to be quickly accessed for reading and writing tasks, and doesn't always need to be non-volatile - susceptible to data loss given a power loss.
Computer storage, on the other hand, almost always needs to be non-volatile. Hard disks, CD-ROMs, and DVDs are all considered examples of computer storage. Computer storage is generally capable of storing much larger volumes of data than computer memory. The downside to storage is that reading and writing tasks take much longer than with memory. But each form has its own uses in the modern computer.
Computer memory is generally reserved for data concerning tasks the computer is currently performing, while storage is used to keep programs and long-term data. One should take note that these are general roles and memory can certainly perform the function of storage in less-demanding applications, and vice versa.
As of now, standard home computers are available with a range of about one to four gigabytes (1024^4 bits) of memory and 100 to 500 gigabytes (GB) of storage. DVDs have about a 4.7 to 8.5 GB capacity, while the newer HD-DVDs and Blu-Ray disks have roughly 15 to 50 GB capacities.
The future holds very exciting prospects for storage. New technology such as holographic, versatile discs and 3D optical data storage discs offer capacities of up to 3.9 Terabytes (830 times the capacity of a DVD). Who would have thought that a bunch of zeros and ones could be so exciting?
Paul Symansky is a staff columnist for The Heights
. He welcomes comments at symansky@bcheights.com.
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