Editing Self-modifying code (section)

==History==
The [[IBM SSEC]], demonstrated in January 1948, had the ability to modify its instructions or otherwise treat them exactly like data. However, the capability was rarely used in practice.<ref name="Bashe-Buchholz-Hawkins-Ingram-Rochester_1981"/> In the early days of computers, self-modifying code was often used to reduce use of limited memory, or improve performance, or both. It was also sometimes used to implement subroutine calls and returns when the instruction set only provided simple branching or skipping instructions to vary the [[control flow]].<ref name="Miller_2006"/><ref name="Wenzl-Merzdovnik-Ullrich-Weippl_2019"/> This use is still relevant in certain ultra-[[Reduced instruction set computer|RISC]] architectures, at least theoretically; see for example [[one-instruction set computer]]. [[Donald Knuth]]'s [[MIX (abstract machine)|MIX]] architecture also used self-modifying code to implement subroutine calls.<ref name="Knuth_MMIX"/>