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  2. Conventional memory - Wikipedia

    en.wikipedia.org/wiki/Conventional_memory

    Memory areas of the IBM PC family. In DOS memory management, conventional memory, also called base memory, is the first 640 kilobytes of the memory on IBM PC or compatible systems. It is the read-write memory directly addressable by the processor for use by the operating system and application programs.

  3. RAM limit - Wikipedia

    en.wikipedia.org/wiki/RAM_limit

    In the original IBM PC, the basic RAM limit is 640 KB. This is to allow for hardware addressing space in the upper 384 KB ( upper memory area (UMA)) of the total addressable memory space of 1024 KB (1 MB).

  4. DOS memory management - Wikipedia

    en.wikipedia.org/wiki/DOS_memory_management

    In IBM PC compatible computing, DOS memory management refers to software and techniques employed to give applications access to more than 640 kibibytes (640*1024 bytes) (KiB) of "conventional memory". The 640 KiB limit was specific to the IBM PC and close compatibles; other machines running MS-DOS had different limits, for example the Apricot ...

  5. Upper memory area - Wikipedia

    en.wikipedia.org/wiki/Upper_memory_area

    In DOS memory management, the upper memory area (UMA) is the memory between the addresses of 640 KB and 1024 KB (0xA0000–0xFFFFF) in an IBM PC or compatible. IBM reserved the uppermost 384 KB of the 8088 CPU 's 1024 KB address space for BIOS ROM , Video BIOS , Option ROMs , video RAM, RAM on peripherals, memory-mapped I/O , and obsoleted ROM ...

  6. IBM Personal Computer - Wikipedia

    en.wikipedia.org/wiki/IBM_Personal_Computer

    The IBM Personal Computer (model 5150, commonly known as the IBM PC) is the first microcomputer released in the IBM PC model line and the basis for the IBM PC compatible de facto standard. Released on August 12, 1981, it was created by a team of engineers and designers at International Business Machines (IBM), directed by William C. Lowe and ...

  7. IBM Personal Computer AT - Wikipedia

    en.wikipedia.org/wiki/IBM_Personal_Computer_AT

    The IBM Personal Computer AT (model 5170, ... Maximum onboard RAM (KB) FDD HDD Notes Ref(s). AT 5170-068 August 1984: June 1987: ISA, 16-bit 8 3 Intel 80286: 6 256 KB

  8. Expanded memory - Wikipedia

    en.wikipedia.org/wiki/Expanded_memory

    Expanded storage was a feature on IBM mainframes providing additional memory outside of the main system memory, first introduced with the IBM 3090 high-end mainframe series in 1985. [8] Expanded storage could not be directly addressed by applications; an MVS feature known as "window services" enabled applications to allocate movable windows to ...

  9. Extended memory - Wikipedia

    en.wikipedia.org/wiki/Extended_memory

    Extended memory is located above 1 MB, includes the high memory area, and ends at 16 MB on the Intel 286 and at 4 GB on the Intel 386DX and later.. In DOS memory management, extended memory refers to memory above the first megabyte (2 20 bytes) of address space in an IBM PC or compatible with an 80286 or later processor.