Storage technology is also improving exponentially. Before the invention of computers, automated information processing systems used punched cards for storage. The popular IBM card could store up to 80 characters, punched one per column. The position of the rectangular holes determined which character was stored in a column. We see the code for the ten digits, 26 letters and 12 special characters below. 1 2
Punch card storage was not very dense by today’s standards. The cards measured 3 ¼ by 7 3/8 inches, 3 and a deck of 1,000 was about a foot long. Assuming that all 80 columns are fully utilized, that works out to about 48,000 characters per cubic foot, which sounds good until we compare it to PC thumb drives which currently hold up to 8 billion characters.
Every type of data – character, audio, video, etc. – is stored using codes of ones and zeros called bits (short for binary digits). 4 Every storage technology distinguishes a one from a zero differently. Punched cards and tape used the presence or absence of a hole at a particular spot. Magnetic storage differentiates between ones and zeros by magnetizing or not magnetizing small areas of the media. Optical media uses tiny bumps and smooth spots, and electronic storage opens or closes minute transistor “gates” to make ones and zeros.
We make progress both by inventing new technologies and by improving existing technologies. Take, for example, the magnetic disk. The first commercially available magnetic disk drive was on IBM's 305 RAMAC (Random Access Method of Accounting and Control) computer, shown below.
IBM shipped the RAMAC on September 13, 1956. The disk could store 5 million characters (7 bits each) using both sides of 50 two-foot-diameter disks. Monthly rental started at USD 2,875 (USD 3,200 if you wanted a printer) or you could buy a RAMAC for USD 167,850 or USD 189,950 with a printer. (In 1956, a cola or candy bar cost five cents and a nice house in Los Angeles USD 20,000).
Contrast that to a modern disk drive for consumer electronic devices like portable music and video players. The capacity of the disk drive shown here is about 2,700 times that of a RAMAC drive, and its data access speed and transfer rate are far faster, yet it measures only 40x30x5 millimeters, weighs 14 grams, uses a small battery for power. The disk itself is approximately the size of a US quarter dollar.
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