also: コンベンショナルメモリ
noun
conventional memory
In DOS-based systems, the first 640 KB of RAM accessible to programs without special memory management.
DOS時代のプログラムは、コンベンショナルメモリーの制限に悩まされることが多かった。
Programs in the DOS era often struggled with the limitations of conventional memory.
Borrowed from English 'conventional memory', a technical term from early PC architecture.