Abstract: A method of providing redundancy in an electrically alterable memory divided into addressable blocks within the memory. The electrically alterable memory should have more available blocks than required by the firmware. The method includes the steps of testing the memory to create block status information about good versus bad blocks, writing the block status information into a table in the electrically alterable memory, reordering the table so that contiguous series of entries in the table point only to good blocks, and then providing a block status array comprising block select registers which are initialized with the corresponding ones of the contiguous series of entries so that a nominal address to a bad block is redirected to a good block.

Abstract: A microcomputer interval counter circuit for detecting the time interval between input signals and for determining when the detected time interval exceeds a preset time interval.The interval counter circuit includes a latch connected to a bus of the microcomputer for storing the preset time interval duration, a counter circuit connected to the latch and to the microcomputer clock for decrementing a number stored in the counter and producing a timing indication as an interrupt to the microcomputer processor, and an OR gate connected to load the counter from the latch when an input signal is received, or when the counter circuit fully decrements.

Abstract: A digital signal bypass circuit including a two terminal clock input for supplying a clock input signal with a predetermined first frequency. A divide-by-two squaring circuit is also provided which is input for synchronously translating the clock input signal into an output signal having a frequency one-half of the predetermined first frequency. A bypass circuit is provided which is connected to the clock input and responsive to the clock input signal applied thereto, the bypass circuit being operative to disable the divide-by-two squaring circuit so that the output signal has a frequency equal to the predetermined first frequency.