Browse Prior Art Database

Hardware Zone Fault Monitor

IP.com Disclosure Number: IPCOM000084749D
Original Publication Date: 1976-Jan-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 2 page(s) / 13K

Publishing Venue

IBM

Related People

Hornung, LM: AUTHOR

Abstract

Memory space or portions thereof, in read-only storage (ROS), is divided into zones. The zone boundaries are physical rather than functional.

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Hardware Zone Fault Monitor

Memory space or portions thereof, in read-only storage (ROS), is divided into zones. The zone boundaries are physical rather than functional.

The hardware monitor compares the address for each reference to the monitored portion of memory with a Zone Fault List. When a "hit" is detected an interrupt is executed to the Monitor Supervisor. The Supervisor determines which zone and which entry point to that zone is involved, by making reference to the return address of the last level program status. The Supervisor may select an alternate address from which to continue execution or may decide to enter the zone regardless. This decision depends, in part, on the controls and enhancements provided by the monitor.

By providing the monitoring function in hardware, "breakpoints" need not be embedded within the application's code. Nor do breakpoints need to be identified in anticipation of their need. Nor does an effective performance degradation occur.

By detecting a "zone fault" rather than a breakpoint, the cost of the monitor is quite inexpensive. For engineering changes, a simple Zone Fault List will be adequate. Physical zones, the boundaries of which are determined by the values of certain address bits, should be acceptable, although some optimiiztion could be realized by mapping software by function onto the physical zones.

Dynamic change of the list, to any real extent, should not be required. Typical chip selects alone could serve to detect zones for instance, in which case the zone size would be equal to the number of bytes on the chip. Finer resolution to zones of 256 bytes or even as small as 16 bytes or less, is within practical limits. The finer resolution would be accomplished by a decode of lower order address bits for 512-byte zones....