Motorola Corporation

Charles I Peddle

Michael F Wiles

Earl F Carlow

Thomas H Bennett

Rodney H Orgill

Edward C Hepworth

William D Mensch, Jr

Anthony E Kouvoussis

Wilbur L Mathys

Rodney J Means

Gene A Schriber

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.

Digital data processing system with interface adaptor having

A peripheral interface adaptor (PIA) circuit for data processing systems contains memory elements or control registers allowing modification under program control of the logical functions of the PIA. The peripheral interface adaptor includes a plurality of system data bus buffer circuits coupled to a system data bus and further includes peripheral interface buffer circuits coupled to a bidirectional peripheral data bus. The direction of data flow in the peripheral data bus is controlled by a data direction register. Data from the system data bus buffer is entered into an input register, and is transferred from there to an input bus coupled to the control register, a data direction register and a data register. Data from the peripheral data bus, the data direction register and the control register are transferred via an output bus to the system data bus buffers. Control signals are generated by select, read/write control, and register select logic which provides signals on a control bus coupled to the input register, the data register, the control register, and the data direction register to control data transfers between the various buses, registers, and buffer circuits.

Interface adaptor architecture

The peripheral interface adaptor (PIA) circuit for data processing systems contains memory elements or control registers allowing modification under program control of the logical functions of the PIA. A peripheral interface adaptor includes a plurality of data bus buffer circuits coupled to a bidirectional data bus and further includes peripheral interface buffer circuits coupled to a bidirectional peripheral system data bus. A direction of data flow at the peripheral interface data bus is controlled by a data direction register. Data from the data bus buffer is entered into an input register, and is transferred from there to an input bus coupled to the control register, a data direction register and a data register. Data from the peripheral data bus, the data direction register, and the control register are transferred via the output bus to the data bus buffers. Control signals are generated by select, read/write control, and register select logic which provides signals on a control bus coupled to the input register, the data register, and the data direction register to control data transfers between the various buses, registers, and buffer circuits.

Data direction register for interface adaptor chip

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.

N-channel field effect transistor integrated circuit microprocessor

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.

Valid memory address enable system for a microprocessor system

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. The interrupt logic circuitry also stores status information indicative of the occurrence of the first interrupt signal and effects interrogation of that status via the data bus.

Interrupt system for microprocessor system

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.

Microprocessor having index register coupled to serial-coupled address

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.

Microprocessor interrupt logic

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.

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. When the second and third coupling circuits are both simultaneously activated in response to the control circuit, digital information present at the counter inputs is effectively latched and temporarily stored in the circuit formed by the counter and the second and third coupling circuits. The processor also includes a program register coupled between the first and second buses for temporarily storing digital information received from the counter means by means of a fourth coupling circuit, which operatively couples the outputs of the counter to inputs of the program register to effect transferring digital information from the counter outputs to the program register inputs in response to the control circuit. Fifth and sixth coupling circuits operatively couple the program register outputs to the first or second bus in response to the control circuit to effect transferring digital information from the program register to the first or second buses, respectively.

Processor including incrementor and program register structure

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.

Master slave registers for interface adaptor

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.

Bus switch coupling for series-coupled address bus sections in a

An MOS (Metal-Oxide-Semiconductor) integrated circuit includes four dedicated registers thereon, two of which are 'write only' registers having the capability of being written into, but not read from, by means of buffer circuitry for coupling a bidirectional data bus to the dedicated registers. The other two dedicated registers are 'read only' registers having the capability of being read from, but not written into, by means of the buffer circuitry. The integrated circuit chip is itself addressable by means of a plurality of address conductors of an address bus coupleable to the integrated circuit chip, and the four dedicated registers within the integrated circuit chip are further addressable by means of an additional address conductor called a register select address line. A control input conductor is coupled to the integrated circuit chip and is used to control the direction of data flow of the buffer circuitry and is also used in conjunction with the register select address line to select one of four dedicated registers. This provides the advantage of reducing the number of external connections required for the integrated circuit chip, and is possible only because the registers are dedicated.

Logic circuitry for selection of dedicated registers

A digital system comprises a plurality of metal-oxide-semiconductors (MOS) chip random access memory (RAM) and read only memory (ROM) and peripheral interface adaptor circuits used as part of the computer coupled to a common bidirectional data bus which is coupled to and controlled by a microprocessor unit (MPU) chip. The digital system uses a multi-level interrupt circuit arrangement including a masked interrupt request input responsive to a multi-plexed interrupt request from peripheral circuits of the system and a non-masked interrupt request input which activates circuitry internal to the microprocessor chip for bypassing program control in initiating an interrupt sequence.

Multiple interrupt microprocessor system

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.

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Norristown, PA, United States of America

Charles I Peddle