SIMCHECK utilizes state-of-the-art components for generating timing signals which are not dependent on the processor clock. These are silicon time delay circuits which are accurately trimmed at the factory using laser technology prior to encapsulation. Once assembled, these parts cannot be adjusted and they are expected to remain stable within SIMCHECK's +/-5nS accuracy for the life of the product. While these devices do no exhibit timing variations, they may become defective, like any other parts. For protection against this (remote) possibility, we have outlined the following simple procedure:
The customer may test 2-3 memory modules of various access times (e.g. 1 module at 50-60nS, and another at 70-80nS) and keep them marked with their access time for periodic reference. Every three months, the customer should re- test these reference modules to verify that the same reading (+/-5nS) are still achieved.
SIMCHECK also uses a programmable voltage source for the device under test. This source is being set at the factory for 4.5V, 5.0V, and 5.5V (at no load) to within +/-250mV. The settings use 1% fixed resistors, which may be adjusted by replacement. Calibration check is made by selecting SIMCHECK DIAGNOSTIC MODE 1, which automatically cycles through the voltage levels. The SIMCHECK DIAGNOSTIC MODE is also described in the SIMCHECK manual.
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