Abstract: A pattern generator for an integrated circuit tester includes an instruction memory storing addressable instructions (INST) and reading out each instruction when addressed by an address (ADDR) supplied as input thereto. An instruction processor receives each instruction read out of the instruction memory and alters the address input to the instruction memory in accordance with the received instruction so that the instruction memory reads out a next instruction. The instruction processor, which includes a conventional return address stack, is capable of executing conventional address increment, call and return instructions. The instruction processor is also capable of executing a temporary return instruction (TEMP) by incrementing its current address output to produce a new return address, by setting its address output to the value of a return address previously saved in the stack, by popping the saved return address from the stack, and by pushing the new return address onto the stack.

Abstract: An integrated circuit (IC) tester organizes an IC test into a succession of test cycles, each test cycle being subdivided into four segments. The tester includes a separate tester channel for carrying out a test activity at each IC pin during each segment of the test cycle. The tester also includes a separate pattern generator for each channel. Each pattern generator concurrently generates four vectors at the start of each test cycle. Each vector tells the channel what activity it is to carry out during a separate segment of the test cycle. Each pattern generator includes a low-speed vector memory storing large blocks of vectors at each address and a cache memory system for caching blocks of vectors read out of the vector memory at a low frequency and then reading vectors out in sets of 16 at the higher test cycle frequency. A vector alignment circuit selects from among the cache memory output vectors to provide the four vectors to the channel for the test cycle.

Abstract: An algorithmic pattern generator produces an output data value during each cycle of a clock signal. The pattern generator includes an addressable instruction memory reading out an instruction during each clock signal cycle. A memory controller normally increments the instruction memory's address during each clock signal cycle, but may jump to another address N+1 clock signal cycles after receiving a CALL, RETURN, REPEAT or BRANCH command from an instruction processor. The instruction processor normally executes the instruction read out of the instruction memory during each clock signal cycle and provides a data field included in the executed instruction as the pattern generator's output data. Other fields of the instruction reference a command the instruction processor sends to the memory controller.

Abstract: A method for making a processor system immune to circuit failure caused by external noise using mirrored processors, and a recovery unit integral with the method, are disclosed. Identical addresses and data information is generated in each of two processors. The data is then partitioned into registers and Error Correction Codes (ECC's) are generated for the data. The address, data, and ECC information for each processor is then interlaced in a data structure. The interlaced structures of each processor are then compared. If the comparison yields no errors, the data is checkpointed in the recovery unit; if an error is detected, a recovery sequence can be initiated after the check-stop operation, whereby the system is restored to the last error-free checkpointing operation.

Abstract: An integrated logic circuit having a novel layout in a semiconductor substrate. The area required for the circuits within the substrate is substantially less than that of prior layouts. Each circuit includes a first device including an elongated impurity region and a set of other impurity regions either in, or in contiguous relationship with, the elongated region; to form a set of diode junctions. The elongated region is capable of containing a predetermined maximum number of the other impurity regions. A second device is located adjacent the narrow side of said first device. A first set of first level conductors extends over the elongated region orthogonally with respect to the elongated direction and are interconnected to selected ones of the other impurity regions. Another conductor is a second level atop the substrate is connected to an impurity region of the second device and extends substantially parallel to the elongated direction.

Abstract: An integrated logic circuit having a novel layout in a semiconductor substrate. The area required for the circuits within the substrate is substantially less than that of prior layouts. Each circuit includes a first device including an elongated impurity region and a set of other impurity regions either in, or in contiguous relationship with, the elongated region to form a set of diode junctions. The elongated region is capable of containing a predetermined maximum number of the other impurity regions. A second device is located adjacent the narrow side of said first device. A first set of first level conductors extends over the elongated region orthogonally with respect to the elongated direction and are interconnected to selected ones of the other impurity regions. Another conductor in a second level atop the substrate is connected to an impurity region of the second device and extends substantially parallel to the elongated direction.