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Browse Prior Art Database

Variable Priority Interruption System

IP.com Disclosure Number: IPCOM000074846D
Original Publication Date: 1971-Jun-01
Included in the Prior Art Database: 2005-Feb-23
Document File: 2 page(s) / 23K

Publishing Venue

IBM

Related People

Hellerman, L: AUTHOR

Abstract

Shown is an improved arrangement for allocating main storage to a central processor and to a channel. Signals 2 and 3 indicate that a channel buffer contains a message that can be transferred to main storage, but that the buffer is not full and that a conventional interrupt is unnecessary. A signal 4 indicates that in its current sequence of microinstructions, the CPU will not access main storage for a predetermined number of machine cycles that is appropriate to permit the channel to access main storage. Signal 4 is provided by a one-bit field in the CPU control storage word 5. This field is prearranged according to the following microinstructions in a sequence, and thus identifies times when main storage will not be accessed by the CPU for the predetermined number of machine cycles.

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Variable Priority Interruption System

Shown is an improved arrangement for allocating main storage to a central processor and to a channel. Signals 2 and 3 indicate that a channel buffer contains a message that can be transferred to main storage, but that the buffer is not full and that a conventional interrupt is unnecessary. A signal 4 indicates that in its current sequence of microinstructions, the CPU will not access main storage for a predetermined number of machine cycles that is appropriate to permit the channel to access main storage. Signal 4 is provided by a one-bit field in the CPU control storage word 5. This field is prearranged according to the following microinstructions in a sequence, and thus identifies times when main storage will not be accessed by the CPU for the predetermined number of machine cycles. An AND circuit 6 responds to the conditions of lines 2, 3 and 4 to operate a portion 7 of the control store to carry out the function requested by the channel.

The system illustrated can be extended to various other facilities besides main storage. An additional field in the control word 5 identifies whether the facilities will be available for a suitable number of cycles, and a separate portion of the control store is provided for controlling operations on these shared facilities.

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