In early PCs, managing memory (RAM) was a huge headache. The PC had more confusing memory types than any computer in history as its architecture was pushed, patched and expanded to meet the demand for more and larger applications. The PC's DOS operating system in the 1980s was designed to address no more than one megabyte (1MB) of memory. Today, 4,000 times as much is entry level.
In the first decade of the PC, technicians had to deal with conventional memory, upper memory, high memory, extended memory and expanded memory (EMS). Countless books were written on PC memory management, and third-party utilities were created to manage memory better (see QEMM
). There were even classroom courses on the subject.
Eventually, subsequent DOS versions (see DOS 6
) and especially Windows, added the necessary memory management to eliminate this manual task. See PC operating environments
, memory allocation
, memory protection
and DOS memory manager
Memory Allocation in a PC
This shows how the first megabyte of RAM was used in early PCs.