Abstract: The present invention describes a novel method and apparatus for sampling an input/output pin of an electronic device at high speeds, comprising the steps of: driving the device input/output pin through a series resistor with a middle voltage between the high and low voltages of the device; sampling and latching the voltage at the input/output pin; comparing the latched voltage at the device input/output pin with a high threshold voltage which is between the high voltage of the device and the middle voltage; comparing the latched voltage at the device input/output pin with a low threshold voltage which is between the low voltage of the device and the middle voltage; and using the results of the two comparisons to determine whether the device input/output pin is driving high, driving low, or in an input mode.

Abstract: In a circuit system simulation model which may comprise a combination of physical dynamic circuit devices to be modeled, of physical static circuit devices to be modeled, and of means for controlling at least the operating sequence of the physical devices, a method is provided for exercising the circuit devices which comprises segregating strobe input signals from nonstrobe input signals to be presented to each circuit device and preserving order of strobe input transitions relative to each other and to nonstrobe input transitions while ignoring the order of nonstrobe input transitions relative to one another when presenting a sequence of input patterns to each circuit device.

Abstract: A simulation model is provided which comprises a combination of the physical device to be modeled and means for controlling the physical device at normal operating speeds so as to avoid loss of data or of accumulated functions. Specifically, the physical device to be modeled is connected through a micro-system simulation means which can accept any of a wide variety of external devices and which includes the logic circuitry and control means necessary to allow the physical device to be stimulated and the resulting behavior observed under external control. Data and logic state patterns are preserved by effective control of the starting, stopping, cycling and resetting of the physical device.