IN-CIRCUIT EMULATOR

摘要

A source-level run-time software code debugging instrument (10) includes a target access probe ('TAP') (12) and a communications adapter ('COMDAP') (14) that process emulation commands provided by source-level debugging software operating on a host computer. The TAP includes a TAP CPU (28) that receives target CPU input signals and delivers target CPU output signals for controlling the execution of software code by the target circuit in accordance with command signals provided by the host computer. The TAP also includes a programmable logic cell array (24) and a RAM (34). The TAP logic cell array routes command and data signals to and from the TAP CPU, and the RAM stores an in-circuit emulation ('ICE') program used by the TAP to operate the target circuit. The COMDAP is physically separate from the TAP and provides an interface between the host computer and the TAP. The COMDAP includes a programmable logic cell array (44) and an EPROM (46). The COMDAP logic cell array routes command and data signals to and from the COMDAP, and the EPROM stores the commands for configuring the signal paths within the TAP and COMDAP logic cell arrays and stores the TAP ICE program. A flat cable assembly (16) provides a high-speed signal communications link between the TAP and the COMDAP. The TAP uses certain microprocessor signal features and source-level debugging software that runs on the host computer to provide a software engineer with a fully transparent window into the internal functioning of the TAP CPU while executing code in the target circuit environment.