Abstract: A system automatically and continuously monitors the performance of separate servomechanisms operating in each of the axes of numerically controlled machine tools to detect when actual machining errors exceed a predetermined maximum due to any malfunction by comparing actual feedback slide velocity, .DELTA.S.sub.2 /T, (as determined by change, .DELTA.S.sub.2, in a feedback position signal, S.sub.2, over a period of time, T) with the commanded system drive velocity, V, (as determined by the difference between commanded position and position feedback signals, S.sub.1 and S.sub.2, respectively, times a gain factor, K). The difference between .DELTA.S.sub.2 /T and K (S.sub.1 -S.sub.2) is machining error which can be used to detect actual error in any axis for alarm or corrective action.

Abstract: A two-axis image motion detector detects two separate velocity channels through a single optical channel with a single photo detector. A single disc rotates at a substantialaly constant rotational speed and contains a pair of orthogonal grid patterns of different spatial frequencies. Preferably, each grid pattern is at 45.degree. with respect to a radial. An image focused on the grid pattern modulates the carrier frequencies determined by the different grid patterns, thereby generating a composite output in the single photo detector representing the sum of the two image motion channels. Standard filtering and demodulating techniques generate a DC voltage proportional to the image rate for each of the orthogonal axes.

Abstract: Fixed pattern noise compensation is provided for an array of detectors by premeasuring output signals of the detectors under a low (preferably at virtually absolute zero) level of uniform incident energy, converting the measured signal level of each detector to digital signals, and storing the digital signals in a memory for reading out in synchronism with scanning outputs of the detectors during normal system operation. The digital compensation signals are converted to analog form and subtracted from the output signals of the respective detectors during each successive scan cycle of the system operation. To eliminate error from random noise, several noise measurements may be averaged to produce the fixed pattern noise compensation signals.

Abstract: The utility of microelectronic devices and the yield of a microelectronic fabricating process is increased by providing, in addition to the desired circuits, "redundant" circuits of the same type. Each circuit has included, in at least one access lead, a nonvolatile, electrically alterable semiconductor device, which can be "set" to either conduct or not conduct power to the circuit.During testing, only the desired number of devices are rendered accessible by "setting" the semiconductor device to conduct.A microelectronic device having repetitive rows and/or columns for memory cells or logical processors is provided with additional rows and columns. An electrically alterable device is placed in each row and column. Upon the successful test of each row, the row enabling device is set to a conductive state. Any row containing a defective device is not enabled. If additional defects exist, and no redundant rows are available, redundant columns are disabled to isolate the defective devices.