Reference STATE OF THE ART Stan Augarten

ISBN 0-89919-195-9
Index
Scanned

1981
Photo of
The Cutting Edge of IC Technology
The First 294,912-Bit (288K) Dynamic RAM

IBM


Few chips are a dazzling as this one, a 288K dynamic RAM that looks less like an IC than a stylized Navajo rug. Because of its enormous storage capacity - it can store the equivalent of some thirty double-spaced 8©-by-11-inch typewritten pages - it is an impressive technical accomplishment. But it is an experimental chip and probably won't wind up in a product - most likely a computer - for several years. Except for Western Electric, very few firms have produced even a 256K RAM, let alone a 288K model. Despite the chip's extraordinary appearance, it was rather conservatively designed; IBM was less interested in forging new design techniques than in proving that 288K RAMs could be fabricated with existing ones. As a result, this IC is quite slow and uncommonly large - in part because it was made with redundant memory cells that may be turned on if some cells prove defective. Because this IC is bigger than most RAMs, it more prone to manufacturing flaws, and the inclusion of such extra cells saves partially defective chips from the scrap heap (p. 56).

Like a work of art, this chip has a design all its own. It is made up of four 72K memory grids (the circuits with the crisscrossed features between gold-colored columns). The irregular elements in the center are amplifiers; the dark balls are lead-tin connectors for wires linking the chip to the outside world. The gold-colored columns contain decoding and amplifying circuits. A bit may be read out of or written into this IC in 450 billionths of a second, only half the speed of other RAMs. The photo's colors were created by bright lights shone onto the chip. Actual size: 0.149 inches x 0.259 inches. Photo of

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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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