Data processor with I/O area detection

Details Data processor with I/O area detection Data processor with I/O area detection

1988-03-25

1990-07-31

Zache, Raulfe B.

Boots, shoes, and leggings

3642463, 364247, 3642472, 364259, 3642591, 3642597, G06F 300

Patent

active

049454722

ABSTRACT:
A device for detecting whether addresses used for accessing in a memory mapped I/O system are present in the I/O area or not is provided. The device includes a mask register for logically ANDing with an incoming address. The output of the ANDing process is exclusive-ORed with an I/O address register. When an operand fetch is made to an I/O area the fetch is suspended during execution of preceding instructions. When the instruction fetch unit seeks an I/O area address, or the address calculation unit seeks an I/O area address, or data is fetched across a boundary of the I/O area, an exception is activated.

REFERENCES:
patent: 3892957 (1975-07-01), Bryant
patent: 4521846 (1985-06-01), Scalzi et al.
patent: 4561052 (1985-12-01), Tateno
patent: 4742451 (1988-05-01), Bruckert et al.
Microcomputer Architecture & Programming, John F. Wakerly, John Wiley & Sons, Inc., 1981, pp. 301-323.

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