Abstract: A nonvolatile memory (28) in a data processor (10) is capable of being progressively programmed and/or accessed in a user determined number of sections. A user can program and/or access what appears to the user to be reprogrammable nonvolatile memory (28) at a same address when in actuality the user is programming and accessing sequential sections of nonvolatile memory (28). Nonvolatile information stored in nonvolatile control bits (20) is used to control which section of the nonvolatile memory is connected to a communication bus and is thus accessible to the user. When the user desires to write and/or access a new section of nonvolatile memory (28), either the user directly asserts one of the nonvolatile control bits (20) using software, or the nonvolatile control (24) asserts one of the nonvolatile control bits (20) using hardware.

Abstract: An improved media filtration apparatus includes an upper tank and lower filtrate compartment, filter media interposed between the upper tank and filtrate compartment for filtering dirty liquid as it is communicated from the upper tank into the filtrate compartment, a conveyor for indexing the filter media in the upper tank and a take-up mechanism including a rotatable idler roller assembly including an idler roller for guiding the filter media and being vertically movable in a range of motion actuates a control to start the take-up mechanism when the idler roller reaches a lower limit of its vertical range of motion and stops the take-up mechanism when the idler roller reaches an upper limit of its vertical range of motion.

Abstract: A single-chip microcomputer comprises a central processor unit (100), a random access memory (110), a read only memory (120), internal timing circuitry including a timer counter (131), and three I/O data ports (140, 150, and 160). Included within the instruction set of the microcomputer are a branch on bit set instruction and a branch on bit clear instruction. The branch on bit set instruction is a three-byte instruction in which the first byte represents the op code including a designation of a particular bit to be examined, the second byte represents the address of a memory location in which the designated bit is to be examined, and the third byte represents an offset which when combined with the contents of the program counter designates a memory location to which a branch is to be taken if the designated bit is in fact set. For the branch on bit clear instruction, a branch is performed when the particular bit examined is determined not to be set.

Abstract: An N-channel MOS high voltage detection circuit generates an output when an input voltage (Vin) exceeds a supply voltage (V.sub.DD) by a desired offset voltage. The crossover detection is delayed by pumping more current into an output producing node via a lower resistance field effect transistor having a gate coupled to the input voltage. The output is finally produced when the effect of this transistor is overcome by a second field effect transistor. Switching characteristics may be sharpened by placing a voltage limiting field effect transistor between Vin and the gate of the low resistance field effect transistor.

Abstract: An MOS low voltage detector circuit includes a comparator which compares an internally generated reference voltage with an internally generated non-linear voltage. Both the reference voltage and the non-linear voltage are derived from a supply voltage, and the comparator generates an output whenever the divided down non-linear voltage falls below the reference voltage. This output is supplied to a series of regularly biased MOS inverter stages which not only amplify the comparator output but also amplify the inherent offset error in the comparator itself. Voltage compensating means may also be included in the comparator.

Abstract: An NMOS power on/low voltage reset circuit provides a substantially instantaneous reset enabling signal when a predetermined fraction of the power supply voltage falls below a predetermined reference voltage. In addition, an external capacitor is discharged. A second reset enabling signal is extended until the capacitor is again charged to a predetermined voltage thus allowing the clock oscillators of a microcomputer sufficient time to stabilize. Self test means are also provided. The reset circuit is implemented on the microcomputer chip.