Innovative Ideas & Stepping Stones

Necessity is the mother of invention. But not all her offspring end up equally successful.

Computer engineers recognized the need for efficient, reliable, affordable memory and storage. Many devised solutions, often attracting supporters who invested considerable money and time. Some ideas worked. Others fizzled, yet served as valuable stepping-stones to later technologies. And many, ultimately, proved creative dead ends.

Core Rope Memory

Developed in the mid 1950s, core rope technology used a matrix of ferrite cores and wires for “read only” memory. Because it was relatively immune to electromagnetic interference, military and aerospace applications continued using rope memory into the 21st century.

Bubble Memory

Bubble memory—small, magnetized areas (“bubbles”) on a thin film—seemed a promising technology when Bell Labs first explored it.

By mid 1970s, nearly every major electronics firm was interested. An estimated $1 billion was spent on research. But, eclipsed by hard disk and semiconductor RAM in the 1980s, the bubble popped.

Charge-Coupled Storage Devices?

Charge-coupled storage devices failed. And then triumphed.

Developed at Bell Labs in the 1960s for solid-state storage, CCDs were swiftly surpassed by magnetic disks. They never succeeded as storage. However, astronomers recognized their potential as light sensors. CCDs became a mainstay of digital cameras—honored in the 2009 Nobel Prize in Physics.

IBM 1360 Photo-Digital Storage System

Trillion-bit storage for the first time! An electron beam wrote bits onto small plastic film strips, which were stored in bins and managed by a complex robotic retrieval system. Difficult to keep running, only seven were produced—all for government customers.

Thin Film Memory

Sperry Rand developed this faster variation on core memory. Small glass plates held tiny dots of magnetic metal film interconnected with printed drive and sense wires. Used in the 1962 UNIVAC 1107 for high-speed registers, it proved too expensive for general use.

RCA Selectron Tube

Jan Rajchman at RCA began work in 1946 on Selectron tube memory: vacuum tubes with isolated gates (“eyelets”) that stored individual bits. Complicated and expensive, Selectron tubes were used only in the JOHNNIAC…and later replaced even there with core memory.