I/O Control system having a plurality of access enabling bits fo

Boots – shoes – and leggings

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3642419, 3642842, 364DIG1, 36492795, 364DIG2, 34082503, 395800, G06F 1320, G06F 1300

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051465655

ABSTRACT:
In an I/O port protection device, accessing an I/O device is selectively controlled by a value of a bit stored in a bit map. A CPU instruction accessing a port is allowed direct acceess when the bit value for that port is a zero, but is trapped when the value is a one. A trapped instruction is either prohibited from any accessing or is rerouted for accessing a different I/O port.

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Hamer Hodges, K. J., "Fault-Tolerant Multiprocessor Design for Real-Time Control", Computer Design, vol. 12, No. 12, 1973, Littleton, Mass., USA, pp. 75-81.

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