|Reference||STATE OF THE ART||Stan Augarten|
|An Unexpected Breakthrough|
The First 65,536-Bit (64K) Dynamic RAM
IBM is the world's largest chip-maker, but it's not the most innovative, and its ICs have had considerably less technological impact than the creations of Fairchild, Intel, or Texas Instruments. (Western Electric, the manufacturing arm of the phone company, is the second biggest.) There are two major reasons for this: IBM's chips are used only in its own products, whereas the other firms' ICs are sold on the open market; and, at least in the early years of IC development, IBM lagged behind the IC industry as a whole, being reluctant to adopt this new form of electronics until its ability was fully proved.
Nevertheless, IBM has made many important innovations in semiconductor technology. At a time, in 1975, when most IC companies were struggling to develop the first 16-K RAM (p. 50), IBM surprised the industry with the creation of an experimental 64K dynamic RAM. Only two years later, it began mass-producing it - two to three years ahead of other firms. Although IBM's 64K RAM was the first, the chip was relatively slow and rather large, which reduced production yields, and it used a lot of power. It probably would not have survived on the open market, but it was adequate for IBM's varied purposes.
Because IBM's chips are designed for its own products, they tend to have an unusual architecture. The 64K RAM, which bears little resemblance to the gridded memory chips of other firms, is no exception. IBM chips also contain redundant memory cells - auxiliary cells that can be turned on if other cells are defective, thus rescuing partially broken chips from the junk pile. Pioneered by IBM, redundancy is often employed in the making of high-capacity memory chips.
|A bit may be read out of or into this IC in 300 billionths of a second. The round balls in the center are lead-tin connectors and are used as contacts for wires linking the chip to other devices. the four rows of light yellow paddles in the middle of the memory grids on either side of the chip are miniscule fuses that can be blown to shut off defective memory cells and to steer signals to extra cells. At 0.366 x 0.693 inches, this chip is the largest in the book; later IBM 64K RAMs were almost 50 percent smaller.|
|STATE OF THE ART
©Copyright Stan Augarten
|This book is provided for general reference. The National Museum of American History and the Smithsonian Institution make no claims as to the accuracy or completeness of this work.|
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