Hewlett-Packard Company

William Fleck

John D Hansen

Stan W Bowlin

Lewis S Kootstra

Beth V Jones

Arnold S Berger

A system for coordinating the measurement activity of a plurality of emulators and their associated internal analyzers uses a bus with three signal lines. A READY signal is set false by any emulator that initiates a break (a transition from running user code to running a monitor). The READY signal is set false by the breaking emulator at the very beginning of its break, without waiting for the resumption of the monitor program. The false ready signal is detected immediately by the other emulators, which then break in sympathy. The READY signal is further used to restart all emulators in unison. The emulator that initiated the break remains running its monitor, while the others start their monitors, determine that they did not cause the break, and then in anticipation of a restart, essentially suspend their monitors and prepared to start running user code. As each emulator becomes ready it releases the READY signal. As the last emulator becomes ready, it too releases READY, which then does true. At this all emulators complete their escape from their monitors (which for each of them amounts to just an instruction fetch, or so) and resume execution of their user code.

Method and apparatus for coordinating measurement activity upon a

A system for coordinating the measurement activity of a plurality of emulators and their associated internal analyzers uses a bus with three signal lines. A READY signal is set false by any emulator that initiates a break (a transition from running user code to running a monitor). The READY signal is set false by the breaking emulator at the very beginning of its break, without waiting for the resumption of the monitor program. The false ready signal is detected immediately by the other emulators, which then break in sympathy. The READY signal is further used to restart all emulators in unsion. The emulator that initiated the break remains running its monitor, while the others start their monitors, determine that they did not cause the break, and then in anticipation of a restart, essentially suspend their monitors and prepare to start running user code. As each emulator becomes ready it releases the READY signal. As the last emulator becomes ready, it too releases READY, which then goes true. At this all emulators complete their escape from their monitors (which for each of them amounts to just an instruction fetch, or so) and resume execution of their user code. A four-state state machine in each emulator assists in this, and is in part, advanced through its states by transitions in the READY signal. The four states correspond to: running the monitor, ready to start executing user code, executing user code, and invoking the monitor. A TRIGGER signal is available to allow analyzers to trigger other analyzers, or to cause an emulator to break. An EXECUTE signal is available to allow a single command issued to any emulator to cause target system starts from preselected initial conditions.

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Colorado Springs, CO, United States of America

William Fleck