How did falling memory costs help make graphical user interfaces possible?

The development of graphical user interfaces (GUIs) was fundamentally enabled by the dramatic decline in the cost of computer memory, specifically dynamic RAM (DRAM).1

In the early 1970s, the cost of DRAM was approximately $80,000 per megabyte; by 2001, that cost had plummeted to less than $0.25 per megabyte. This vast reduction in price allowed for the widespread implementation of bit mapping, a technique where every pixel on a display screen is represented by data stored in memory.12

Because GUIs require significant amounts of memory to hold these graphical images—often referred to as bitmaps—the previous high cost of memory made such interfaces prohibitively expensive for general use. As memory became more affordable, it became feasible to store the complex visual elements of a GUI, such as windows, icons, pull-down menus, and display fonts, directly in memory for the computer to render on screen. This shift transformed computing from text-based command lines to the intuitive, visual systems that define modern personal computers.12