4-Kilobit DRAM
The 4-kilobit DRAM is the second major density generation of dynamic random-access memory, a chip holding 4,096 bits, four times the capacity of the 1-kilobit generation that preceded it. It arrived in the early-to-mid 1970s and is significant less for the raw capacity jump than for what happened competitively at this node: the 4-kilobit generation is where the DRAM market stopped being an Intel near-monopoly and became a genuine contest, most pointedly through Mostek's MK4096, which introduced an addressing innovation that became an industry standard.
The defining technical event of the 4-kilobit generation was address multiplexing, introduced commercially at scale with Mostek's MK4096. As memory capacity grew, each chip needed more address lines to select among its cells, and more pins meant larger, costlier packages. Address multiplexing solved this by sending the row address and the column address over the same set of pins in two sequential steps rather than all at once, roughly halving the number of address pins a chip needed. This let the 4-kilobit chip fit in a smaller, cheaper package, and the scheme proved so advantageous that it became the standard way DRAMs were addressed for generations afterward.
The 4-kilobit generation reshaped the competitive landscape of the memory business, ending the sense that one company owned DRAM. Intel's 1103 had defined the 1-kilobit generation and the early market, but at the 4-kilobit node Mostek's MK4096 and its packaging and addressing advantages let a challenger take significant share. This established a lasting pattern in memory: leadership was not permanent and could shift generation to generation to whichever company best combined density, cost, and manufacturing execution. The 4-kilobit generation is the first clear instance of that generational turnover, which would recur repeatedly as the industry evolved.
The address-multiplexing innovation at this node illustrates a general truth about memory scaling: packaging and interface economics matter as much as the memory cell itself. It would have been possible to build a 4-kilobit chip with a full set of address pins, but it would have cost more to package and use. By rethinking how the chip communicated its address, Mostek improved the economics without changing the fundamental storage technology. This lesson — that the way a chip connects to the outside world is a first-class design concern, not an afterthought — recurs throughout the history of memory and processor design alike.
The 4-kilobit generation sits in the regular density progression that organizes the whole DRAM story, but it carries a distinct identity as the standardization node. Where the 1-kilobit generation proved semiconductor memory could beat cores, and later generations pushed density far higher, the 4-kilobit generation is remembered as the one where the physical and electrical conventions of how a DRAM is addressed and packaged got settled in a form that endured. It is a reminder that progress in memory came not only from shrinking cells but from establishing durable standards at specific moments along the way.
Read the 4-kilobit DRAM as the standardization node: a fourfold capacity step whose real legacy was address multiplexing, the pin-saving addressing scheme Mostek's MK4096 popularized, which became a lasting DRAM convention and broke open a memory market that had looked like one company's to keep.