Isolated I / O

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The isolated I / O ( isolated addressing ), and Port-Mapped I / O ( PMIO ), a method for addressing memory cells connected peripheral devices in a microcomputer .

With the more well-known alternative memory mapped I / O , the registers of the peripheral device are mapped to memory locations within the usual address space and controlled as such by the processor. In the case of isolated I / O, on the other hand, an isolated address space is used that is much smaller and is controlled separately from the main memory address space. This address space is also known as the I / O address space. To select the respective address space, an additional signal such as. B. MREQ (Memory Request) is used. The controlling software must have special I / O commands that activate these signals and thus address their own address space.

literature

  • Barry B. Brey: Microprocessors and Peripherals , Maxwell Macmillan International Editions 1988, ISBN 0-675-20884-X