Computer Memory Technology Timeline

1950-70s               1960s                                  1970s→                        1970-80s                  1980s→
Image fo core memory
Core Memory
image of Rod memory
Rod Memory
image of DRAM chip
DRAM Memory
image of Intel EPROM
EPROM
Picture
Bubble Memory
image of a flash memory chip
Flash Memory







The Evolution of Computer Memory

image of a RCA core memory
RCA Magnetic Core Memory Ad (1964)

Early computers in the 1940's used vacuum tubes to store memory. But the memory would be lost if power was taken away, this type of memory is known as Volatile memory.

Efforts began in the late 1940s to find a way to create non-volatile memory. Jay Forrester, Jan A. Rajchman and An Wang would be credited with the development of magnetic core memory, which would allow for recall of memory after power loss. Magnetic core memory would become the dominant form of memory until the development of transistor based memory in the late 1960's.

Also during the 1960's, NCR Computer created their own unique version of magnetic memory technology called "Rod Memory" that was used in their business computers, competing with Magentic Core Memory technology.

By 1970, Transistor based RAM & ROM memory on Integrated Circuits became the industry standard in computer memory. This new technology offered a much smaller component size and cheaper cost than the earlier core memory. Non-volatile Read-only memory (ROM) was now able to store program code.  Volatile Random-access memory (RAM) was able to store data.

A few companies, including Intel, Western Electric, Texas Instruments, Hitachi & Sharp, produced a promising new form of thin-film, nonvolatile memory in the 1970's known as Bubble memory.

Other types of non-volatile memory including erasable programmable read only memory (EPROM) in the 1970's, and electrically erasable programmable read-only memory (EEPROM or Flash ROM) in the 1980's. These types of memory can be erased and reprogrammed, but it was a slow process.

Flash memory was created in the 1980's and works like the earlier EEPROMs, allowing non-volatile reprogrammable storage, but also allows data to be erased and reprogrammed thousands of times  and at very high speeds.



Memory Technology used in Early Computers

  • 1941-44           Magnetic Latching  Relay           Harvard Mark Series
  • 1945-47           Thermal                                         Not Implemented
  • 1940-50           Mechanical                                   Zuse Machines
  • 1946-53           Delay Line                                    EDSAC, EDVAC, UNIVAC I, LEO I, Pilot ACE, SEAC
  • 1940s-53         Electrostatic (Vacuum Tube)      ENIAC, MIT Whirlwind I, IBM 701, IBM 706, IAS
  • 1947-50s         Rotating Magnetic (Drum)          ARC, IAS, IBM 650
  • 1949-60s         Static Magnetic (Core)               MIT Whirlwind, IBM 405, IBM 704, IBM 7090
  • 1964-69           Rod Magnetic (Thin Film)           NCR 315, NCR Century 100
  • 1968-70s         Twistor Magnetic (Thin Film)      Bell System 1ESS - 4ESS
  • 1970-80s         Bubble Magnetic (Thin Film)     Sharp PC 5000, GRiD Compass 1101
 

 

 

Some Memorabilia with Computer Memory

 
 


Silicon Wafers > Computer Memory > Magnetic Storage > MEMS Devices

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