Abstract: A synchronization system synchronizes a first signal with a second signal. Data values of the first signal are stored in a first-in, first-out (FIFO) device in response to strobe signals that latch the first signal. The output of the FIFO device is clocked by clocks of the second signal. Therefore, the signal output by the FIFO device is synchronized with respect to the second signal. If the frequencies of the first signal and the second signal differ, then multiple FIFO devices are used to successively store the data of the first signal. In this regard, the signal output by the plurality FIFO devices has the same frequency as the second signal and has a bit length larger than the first signal.

Abstract: The present invention involves a configurable flip flop having a first data input node, a second data input node, and an output node. The configurable flip-flop includes an inverter coupled to the first data input node. Each of a plurality of configuration lines address a multiplexor and the flip-flop output node for selecting one of the first data input node, the second data input node, or an inverted first data input and coupling the selected one to a multiplexor output. A latch receives the multiplexor output and generates a gated output and an edge triggered output. A configuration bit controlled selector couples either the gated output or the edge triggered output to the configurable flip-flop output node.

Abstract: A programmable logic device having a configurable random access memory (RAM) integrated on a single integrated circuit chip. The configurable RAM has a user selectable logical configuration. In operation, the RAM in accordance with the present invention is addressed by a system address bus and data is provided using a system data bus. The memory array can also be addressed by a control address bus and data read out and loaded into the RAM using a control data bus.

Abstract: The present invention involves a configurable flip flop having a first data input node, a second data input node, and an output node. The configurable flip-flop includes an inverter coupled to the first data input node. Each of a plurality of configuration lines address a multiplexor and the flip-flop output node for selecting one of the first data input node, the second data input node, or an inverted first data input and coupling the selected one to a multiplexor output A latch receives the multiplexor output and generates a gated output and an edge triggered output. A configuration bit controlled selector couples either the gated output or the edge triggered output to the configurable flip-flop output node.

Abstract: A high input impedance CMOS multiplexor. A buffer stage is connected to common outputs of a plurality of N-channel multiplexor switches. A pull up P-channel transistor in this buffer is connected to a voltage source which is equal to the maximum voltage output from one of the plurality of N-channel multiplexor switches. As such, the buffer output can be fully shut off when a logic "1" is output by one of the multiplexor switches. The input impedance of the multiplexor is approximately the input impedance of the buffer or approximately 10.sup.14 ohms.

Abstract: A circuit for coupling ECL level logic signals to NMOS circuitry first translates the ECL logic swing from the range of -1.6 v to -0.8 v up to the range of about +0.5 v to +1.3 v. This is done by driving the source of an enhancement device with the ECL input signal. This has the further benificial effect of compensating for temperature changes and process related variables. The level shifted signal is then applied to a gain stage for amplification and delivery to the using circuits. If the ECL input signal is available in complementary form then the complement can be used to drive the source of the gain stage; otherwise it should be connected to V.sub.ref of the ECL circuitry.

Abstract: An integrated circuit for sequentially receiving a plurality of binary interval numbers, each representing the width of a time interval occurring during optical scanning of a bar coded label, includes first, second, third and fourth sequentially located edges forming a rectangle. The integrated circuit includes input logic circuitry for receiving and temporarily storing the binary interval numbers and a plurality of adders and shift registers for adding predetermined ones of the stored binary interval numbers and storing the resulting sums. The integrated circuit includes a plurality of comparators for comparing predetermined ones of the sums and stored sums to produce a plurality of intermediate signals. Encoding circuitry encodes predetermined ones of the intermediate logic signals to produce a digital character number representing a character scanned on the bar coded label and also includes output circuitry.

Abstract: A digital system including a plurality of metal-oxide-semiconductor (MOS) chip random access memories (RAM), read only memories (ROM) and peripheral interface adaptors coupled to a common bidirectional data bus which is coupled to and controlled by a microprocessor unit (MPU). Each peripheral interface adaptor includes a control register loadable under program control. The contents of the control register control selection of several registers within the interface adaptor. The control register also controls other functions of the peripheral interface adaptor, including determining direction of data movement at the peripheral buffers of the interface adaptor. The contents of the control register of each interface adaptor are monitorable by the microprocessor unit.

Abstract: An N-channel field effect transistor microprocessor includes an arithmetic logic unit, a plurality of working registers and address generating circuitry coupled to an internal bus. Control circuitry is coupled to the arithmetic logic unit, the working registers, and the address generating circuitry for producing control signals for controlling operation of the arithmetic logic unit, the working registers, and the address generating circuitry. The microprocessor requires only a single external power supply, and includes means connected to the external power supply for providing electrical energy to the working registers, the arithmetic logic unit, the control circuitry, and the address generating circuitry in order to effect operation thereof.

Abstract: A digital system includes a microprocessor coupled to a data bus and an address bus. A memory for storing data and instructions is connected to the data bus and the address bus. A peripheral device is connected to an interface adaptor. The interface adaptor is connected to the data bus and the address bus, and performs the function of interfacing between the digital system and a peripheral device, such as a printer or a display device. The microprocessor includes logic circuitry for generating a Valid Memory Address (VMA) output. The VMA output is used to generate an enable signal applied to the memory and the adaptor to enable the memory and the adaptor to be accessed by the microprocessor when the binary address on the address bus is valid and to prevent the memory and the adaptor from being accessed by the microprocessor when the binary address on the address bus is not valid with respect to the microprocessor.

Abstract: A microprocessor system includes a microprocessor, a memory, and an interface adaptor all coupled to a data bus. The interface adaptor is coupled between the data bus and a peripheral device, such as a teleprinter. A first interrupt conductor is connected to the peripheral device and to interrupt logic circuitry in the interface adaptor. A second interrupt conductor is connected to the microprocessor and the interrupt logic circuitry. The interrupt logic circuitry is also coupled to and interrogatable by the microprocessor via the data bus. The interrupt logic circuitry stores interrupt contrl information from the data bus, and generates a second interrupt signal on the second interrupt conductor in response to the stored interrupt control information and an interrupt signal generated on the first interrupt conductor by the peripheral device.

Abstract: A microprocessor includes a data bus and an address bus. The address bus has first and second sections coupled together in series by bus switch circuitry. The microprocessor also includes control circuitry for controlling various data transfers in the microprocessor. The bus switch circuitry includes a plurality of MOSFETs each having their gate electrodes coupled to the control circuitry and having their sources and drains coupled to corresponding bus conductors of the first and second sections of the address bus. A program counter, incrementer and other working registers are coupled between the address bus first section and the data bus. An accumulator register and an arithmetic logic unit are coupled between the second section of address bus and the data bus. An index register for storing information to be utilized in an indexed addressing mode of operation is coupled to both the first and second sections of the address bus and to the data bus.

Abstract: Interrupt circuitry is provided for an MOS integrated circuit microprocessor chip. An input of the microprocessor chip is adapted to having an external interrupt signal applied thereto for interrupting the operation of the microprocessor chip within a digital data processing system. The input is coupled to circuitry which inhibits loading of the next instruction to be executed in response to an interrupt request signal applied to the interrupt request input, and also forces a code into the instruction register in response to the interrupt request signal. The code is substantially similar to the code for a software wait instruction or a software interrupt instruction. Therefore, much of the same circuitry within the microprocessor can be used for executing an interrupt operation, a software wait instruction, or a software interrupt instruction.

Abstract: A method of generating addresses in a microprocessor includes steps of storing first informationrepresentative of a first address in a first register, such as a program counter register. The first information is transmitted to a first address bus in order to effect addressing the contents of a first location represented by the first address. The first information is also transmitted via the address bus to an incrementor-decrementor circuit. The first information is incremented to produce second information representative of the address of the next instruction during the addressing of the first location. The second information is then transmitted to the first register.

Abstract: A processor including a first bus, a second bus, and a control circuit for producing control signals includes a counter having a plurality of inputs and outputs responsive to the control circuit and coupled between the first and second buses for incrementing digital information present at the inputs of the counter. The processor includes a first coupling circuit responsive to the control circuit for coupling the counter inputs to the first bus to effect transferring digital information from the first bus to the counter inputs. A second coupling circuit couples the counter inputs to the second bus to transfer digital information from the second bus to the counter inputs in response to the control circuit. A third coupling circuit couples the counter outputs to the second bus to transfer digital information from the counter output to the second bus.

Abstract: An interface adaptor suitable for use in a microprocessor system includes an input register coupled to a bidirectional data bus of the microprocessor system. The interface adaptor includes a plurality of registers, including a control register and a data register, coupled to the input register by means of an internal input bus. Each of the plurality of registers includes flip-flops which are coupled as slave flip-flops to corresponding flip-flops of the input register. The corresponding flip-flops of the input register function as master flip-flops. The interface adaptor also includes register selection logic circuitry for selecting one of the plurality of registers by electrically coupling its slave flip-flop to the corresponding master flip-flops of the input register.

Abstract: A microprocessor includes a data bus and an address bus. The address bus has first and second sections coupled together in series by bus switch circuitry. The microprocessor also includes control circuitry for controlling various data transfers in the microprocessor. The bus switch circuitry includes a plurality of MOSFETs each having their gate electrodes coupled to the control circuitry and having their sources and drains coupled to corresponding bus conductors of the first and second sections of the address bus. A program counter, incrementer and other working registers are coupled between the address bus first section and the data bus. An accumulator register and an arithmetic logic unit are coupled between the second section of address bus and the data bus.

Abstract: Interrupt circuitry is provided for an MOS integrated circuit microprocessor chip. An input of the microprocessor chip is adapted to having an external interrupt signal applied thereto for interrupting the operation of the microprocessor chip within a digital data processing system. This first input is connected to circuitry which is enabled by a signal from a bit of a condition code register on the microprocessor chip which bit, is set, acts to mask or disenable the interrupt signal, so that the instruction execution operation of the microprocessor chip is not interrupted. A second input of a microprocessor chip is adapted to having a second interrupt signal applied thereto. The second input is connected to other input circuitry which is not enabled by the mask bit of a condition code register. Therefore, the second input acts as a non-maskable interrupt input.

Abstract: Disclosed is an integrated circuit microprocessor with a parallel binary adder whose output can be corrected on-the-fly to provide decimal results. The correction is by logical gating which operates selectively and on-the-fly, that is, while the sum from the output of the binary adder is being transferred to an accumulator. As a result, the same binary adder can provide the binary sum of the operands supplied to it, or the binary coded decimal sum of bcd operands, or the binary coded decimal difference of bcd operands, in a single operating cycle and without the need to recycle the sum of the operands through the adder. This single cycle correction significantly speeds up the operation of the invented microprocessor as compared to known prior art microprocessors which recycle the adder output when a binary coded decimal sum or difference is required.