Abstract: The presence or absence of a property in a computer subsystem is determined using a multiple input shift register (MISR). A subsystem device operates on predetermined test data to produce output data. The MISR operates on the output data to produce a final test value dependent on the output data. The property has a known final MISR value associated with the device under test and the test data. The MISR final test value is read and compared to the known final value for the property. If the two values are the same, the property exists in the system. In a second embodiment, a property from among a set of known possible properties or variations of a property is determined. In a specific application of the second embodiment, the length of a serial access memory (SAM) portion of a video random access memory (VRAM) is determined.

Abstract: The present invention provides an apparatus and method for monitoring the functioning of a special operational mode on an integrated circuit module without the need for a special or dedicated pin. By monitoring the data output pins of the module operation in a special operational mode and premature interruption thereof, is detected. Delayed transition from a state of low impedance to a state of high impedance during the data output cycle is indicative of the special operational mode. The modules which usually have tri-state devices on their output lines are provided with delay circuitry to delay the transition of the tri-state device, during the data output cycle, from a state of low impedance to a state of high impedance while the device remains in a special operating mode.

Abstract: A lithographic mask with an exposure monitor for imaging a gray scale feature. The exposure monitor has abutting regions of differing optical density disposed on the mask for imaging the gray scale feature by taking advantage of diffraction effects. After calibrating gray scale feature size to critical feature size, a gray scale feature may be imaged to monitor critical feature size due to exposure.