Abstract: A system for interfacing a Processor to a Coprocessor using standard bus cycles. The Processor, upon encountering in its instruction stream an instruction having a particular Operation word format, will transfer a Command word following the Operation word to a particular Coprocessor designated by a Coprocessor Identity field in the Operation word. Upon decoding the Command word, the Coprocessor will respond with any of a set of response primitives which define functions which the Coprocessor requires to Processor to perform in support of the Command by the Coprocessor. The interface provides for all functions which the Coprocessor may require, including selective vectoring to appropriate exception handlers.

Abstract: A complementary metal-oxide-semiconductor (CMOS) isolation structure where the field isolation structure between the adjacent areas of different conductivity types has a channel stop doped with boron or phosphorus affected by germanium. The dual use of germanium and a second dopant selected from the group of phosphorus and boron provides a more precisely placed channel stop, since the germanium retards the diffusion of the boron and phosphorus and surprisingly provides improved width effect for the devices in the well where the channel stop is employed. Alternatively, the germanium may be placed in such a manner as to avoid retarding absorption of boron or phosphorus into the field oxide and retard its diffusion over the well of a different conductivity type where it is not desired.

Abstract: A microcomputer prioritizes data operand requests and instruction prefetch requests. Such prioritizing is established by established criteria. The established priority is altered upon the occurrence of a signal. The signal indicates a certain type of data requests. This data request type is deemed to have a higher priority than is typical for a data request. Consequently, in response to receiving the signal which indicates this data request type, the priority is altered so as to be more inclined to perform the data request. This is particularly useful when performing numerous consecutive data operations, such as a co-processor interface operation.

Abstract: In a data processing system, a paged memory management unit (PMMU) translates logical addresses provided by a processor to physical addresses in a memory using translators constructed from page descriptors comprising, in part, translation tables stored in the memory. The PMMU maintains a set of recently used translators in a translator cache. In response to a particular lock value contained in a lock field of the page descriptor for a particular page, the PMMU sets a lock indicator in the translator cache associated with the corresponding translator, to preclude replacement of this translator in the translator cache. A lock warning mechanism provides a lock warning signal whenever all but a predetermined number of the translators in the cache are locked. In response, the PMMU can warn the processor that the translator cache is in danger of becoming full of locked translators. Preferably, the PMMU is also inhibited from locking the last translator in the cache.

Abstract: In a digital signal processing system, a logarithmic arithmetic logic unit which selectively performs multiply/accumulate operations of operands in logarithmic number representation. Direct feed through of operands through an adder/subtractor circuit, even when an addition or subtraction is not effected, eliminates external bypass circuitry. A method for adding and subtracting operands in logarithmic number representation. An adder/subtractor circuit which efficiently effects addition and subtraction of operands in logarithmic number representation over a wide dynamic range.

Abstract: A clock generator is used in a non-volatile memory to generate a timing signal for clocking a sense amplifier. The timing signal duration is timed using circuit features which also affect the rate with which data can be sensed by the sense amplifier. The clock generator includes a reference word line which is analogous to an accessed word line, a memory cell which establishes a reference current analogous to that provided by an accessed cell, and a current mirror which uses the reference current to charge a reference line analogous to a bit line. The duration of the timing signal is established by the reference line reaching a predetermined voltage.

Abstract: A redundant decoder for use in a predecoded memory scheme includes a plurality of predecoding circuits each having an output and each having inputs coupled to selected address signals. The outputs of the predecoding circuits are applied to the inputs of a smaller group of decoding circuit. In addition, the outputs of the predecoding circuits are coupled to the gate electrodes of one of a plurality of series coupled field effect transistors each having a laser blowable fuse coupled across its source drain path. Should one of the decoding circuits prove to be operating improperly, is only necessary to blow the fuses across the individual field effect transistors whose gate electrodes are coupled to the predecoding circuit outputs which served as inputs to the bad gate. In this manner, the output of the stack will go high only when the output of the bad decoding circuit should go high.

Abstract: An integrated circuit has a plurality of outputs which switch to a valid condition at the same time. Because integrated circuits have leads for power supply terminals, there is inductance on these leads. When an output switches logic states, there is a change in current flow so that there is a voltage drop across the inductive lead which is used for power supply coupling. This voltage drop, expressed Ldi/dt, is proportional to the number of outputs which are switched. The worst case for the positive power supply terminal Ldi/dt is when all of the outputs switch from a logic low to a logic high. This worst case is reduced in half by predisposing half of the outputs to one logic state and the other half to the other logic state. This also reduces the worst case for the negative power supply terminal, frequently ground, in half which is the case when all of the outputs switch from a logic high to a logic low.

Abstract: A content addressable memory (CAM) comprising a plurality of CAM cells, each including a static read/write memory (RWM) cell and an EXCLUSIVE OR (XOR) gate which couples a sense line to a ground line only if the logic state of the operand bit stored in the RWM cell does not match the logic state of an operand bit presented to the CAM cell. By arranging a selected subset of the CAM cells so that the XOR gates thereof act upon a first portion of either the sense line or the ground line while the balance of the CAM cells are arranged so that the XOR gates thereof act upon a second portion of that same line, a single coupler interposed between the first and second portions can be selectively disabled by a mask signal to simultaneously mask all of the bits stored in the subset of CAM cells during the matching operation of the CAM. If appropriate, the mask signal may comprise the bit stored in a particular one of the CAM cells.

Abstract: A method of using removable sidewall spacers to minimize the need for mask levels in forming lightly doped drains (LDDS) in the formation of CMOS integrated circuits. Aluminum or chemical vapor deposition (CVD) metals such as tungsten are suitable materials to form removable sidewall spacers which exist around CMOS gates during heavily doped source/drain region implants. Conformal materials such as CVD polysilicon may also be employed for this purpose. The sidewall spacers are removed before implantation of the lightly doped drain regions around the gates. This implantation sequence is exactly the reverse of what is currently practiced for lightly doped drain formation.

Abstract: A stereo decoder is provided for decoding an encoded stereo signal. In one form, the encoded stereo signal is digitized and coupled to two sampling circuits. By selectively sampling the encoded signal relative to a stereo pilot signal contained in the encoded signal, both a left-hand audio signal and a right-hand audio signal may be separately recovered from the encoded signal and latched. A phase locked loop monitors the phase of the stereo pilot signal relative to the encoded signal and controls the time sampling of the encoded signal at predetermined phases of the pilot signal. The stereo decoding may also be performed by using analog circuitry to directly time sample the encoded stereo signal. In an analog approach, the time sampled output signal must be low pass filtered to provide decoded stereo output signals.

Abstract: A modulo arithmetic unit and method for providing a sum of first and second numbers is provided. In one form, a first adder calculates a first sum which is equal to the arithmetic sum of the first and second numbers. A second adder is provided for adding the first number to an offset value equal to (2.sup.X -M), where X defines the number of bits of the number system used, M is a predetermined modulus and X and M are integers. A third adder operates in parallel with the first adder to calculate the sum of the output value of the second adder and the second operand to provide a second output sum and a carry output bit. In another form, only two adders are utilized wherein the first adder calculates a first output sum of the first and second numbers, and the second adder calculates the sum of the first output sum and the offset value. Both illustrated forms utilize a multiplexer which outputs one of the two calculated output sums depending upon whether a wraparound of an upper modulus boundary occurred.

Abstract: A circuit which converts differential outputs of a fully differential amplifier to a single output using a buffer amplifier is provided. The fully differential amplifier has common-mode feedback provided by a differential feedback stage. An input of the common-mode differential feedback stage is connected to a predetermined one of the differential outputs to maintain the predetermined output at a reference voltage potential. The buffer amplifier uses diffused or well resistors and a single-ended differential amplifier. The buffer amplifier has a balanced structure which minimizes noise and resistor nonlinearity output errors. The circuit also maintains excellent power supply rejection.

Abstract: A bus master is prevented from utilizing a communication bus during a current sample interval if the utilization rate of the communication bus during the immediately preceeding sample interval exceeded a selected limit.

Abstract: A process is disclosed for fabricating complementary insulated gate field effect transistors including doped field isolation regions and optional punch through protection. In one embodiment of invention, a silicon substrate is provided which has N-type and P-type surface regions. First and second masks are formed overlying active areas of the two surface regions. A third mask is then formed overlying the first region and the first mask. P-type impurities are implanted into the second region with an implant energy which is sufficient to penetrate through the second mask but insufficient to penetrate through the third mask. A second P-type implant is performed with an implant energy insufficient to penetrate through either mask. The first implant will aid in preventing punch through while the second implant dopes the field region. A fourth mask is then formed overlying the second region and the second mask.

Abstract: A method for determining the etch bias of a particular semiconductor device feature layer material in a given etch process employing a hard mask reference material that changes very little or not at all during the etch under examination, and using a cross-sectional examination of the critical dimensions to determine the bias. Silicon dioxide would be a suitable hard mask material for a plasma etch bias study, for example. Preferably, a scanning electron microscope would determine the etch bias in one microphotograph. The need for optically taking two or more separate measurements to optically determine the etch bias, and the possiblility for incorporating error between measurements, is eliminated. In addition, the contribution of photoresist erosion to the etch bias of the device feature layer may be independently determined.

Abstract: An integrated circuit has an identifying circuit coupled to an input. The input has ESD protection. The identifying circuit has a fuse which is in one of two possible states to provide the identifying information. A power on reset circuit provides a pulse in response to application of power to the integrated circuit. A current path between a power supply terminal and the input is provided in response to the power on reset pulse when the fuse is in one state. This current path is blocked when the fuse is in the other state. A user is thus provided with identifying information by the presence or absence of a current path at the input at the time when power is applied.

Abstract: A memory, which has an amplifying circuit which provides a pair of differential signals representative of data contained in a memory cell selected by an address, has an output driver which receives this pair of differential signals on a pair of input lines. The output driver is tri-stated in response to an address transition so that the output driver provides only either valid data or a high impedance. The data provided by the differential signals is latched on the input lines by data latches after a predetermined time delay if new valid data has not appeared. The data latches used add less capacitance to the pair of input lines than those used previously.

Abstract: A process for forming an insulated gate field effect transistor (IGFET) having a semiconductor gate with a central portion and end portions on either side thereof where the portions are of two different conductivity types. Typically, a central portion of the gate, such as a doped polysilicon portion of a first conductivity type, is flanked by end portions near the source/drain regions, where the end portions are doped with an impurity of a second conductivity type. The central portion of the gate is formed by conventional gate patterning whereas the end portions are formed by typical procedures for forming sidewall spacers using a conformal layer of in situ doped polycrystalline silicon (polysilicon) or other semiconductor material and an anisotropic etch.

Abstract: A system for interfacing a processor to a Coprocessor using standard bus cycles. The processor, upon encountering in its instruction stream an instruction having a particular Operation word format, will transfer a Command word following the Operation word to a particular Coprocessor designated by a Coprocessor Identity field in the Operation word. Upon decoding the Command word, the Coprocessor will respond with any of a set of response primitives which define functions which the Coprocessor requires to Processor to perform in support of the Command by the Coprocessor. The interface provides for all functions which the Coprocessor may require, including selective vectoring to appropriate exception handlers.