Abstract: An access circuit for data swapping between two computers and a computer system including the access circuit. Each computer including an address bus for supplying addresses and a data bus for transferring data. The access circuit includes a register file and two address decoder circuits. The register file has a plurality of storage locations for storing data. The register file has dual data ports capable of simultaneous data transfer via the first data port with a first data storage location and via the second data port with a second, different storage location. Each address decoder is connected to the address bus of a corresponding computer and the register file. The address decoders translate an address received on the address bus to a storage location of the register file. Two handshakes circuits are connected to respective address decoders and digital computers. The first and second address decoders are connected to each other.

Abstract: A multifunction access circuit for use with first and second digital computers each having an address bus for supplying addresses and a data bus for supplying data. The access circuit has an address decoder with inputs for the address bus from the first computer, and an address translator circuit having address inputs for addresses supplied by the address bus of the first computer and outputs for translated addresses to the address bus of the second computer. The address translator circuit also has registers selectable by the address decoder and data inputs to program the registers so selected with data from the data bus from the first computer. Also in the access circuit is a port circuit with registers controlled by the address decoder for entry of address information from the data bus of the first computer and assertion of the address information on the address bus of the second computer.

Abstract: A memory access system for use with a graphics processor having an address bus, a data bus and a set of control lines. An address translator circuit connected to the address bus of the graphics processor supplies a translated address to a memory upon receipt of an address from the graphics processor. A logic circuit responds to a write signal to automatically increment the translated address and responds to a control signal to return to the translated address. Control circuitry connected to the logic circuit responds to a read signal to supply the control signal to the logic circuit.

Abstract: A computer graphics system includes a host computer and a graphics processor. The graphics processor includes a control register. When the graphics processor writes to the control register it simultaneously generates a predetermined address on a local address bus and supplies data on a local data bus identical to data to be written into the control register. A shadow register circuit connected to both the host computer and the graphics processor includes a shadow register and first and second address decoders. The first address decoder enables a write from a local data bus into the shadow register upon detection of the predetermined address. The second address decoder enables a read from the shadow register via a host data bus upon detection of the predetermined address on a host address bus.

Abstract: A graphics computer system including a host computer and a graphics processor. The host computer has a host data bus and a host address bus. A first video memory stores color codes corresponding to a display. The first video memory is connected to the host computer permitting it to specify the color codes. A first palette connected to the first video memory has a first look-up table memory for recalling color data words corresponding to color codes received from the first video memory. The first palette is connected to the host computer permitting it to specify the color data words stored in the first look-up table memory. The graphics processor has a local data bus and a local address bus. A second video memory stores color codes corresponding to a display, the graphics processor specifying the color codes stored in the second video memory. A second palette connected to the second video memory has a second look-up table memory.

Abstract: A multifunction access circuit for use with first and second digital computers each having an address bus for supplying addresses and a data bus for supplying data. The access circuit has an address decoder with inputs for the address bus from the first computer, and an address translator circuit having address inputs for addresses supplied by the address bus of the first computer and outputs for translated addresses to the address bus of the second computer. The address translator circuit also has registers selectable by the address decoder and data inputs to program the registers so selected with data from the data bus from the first computer. Also in the access circuit is a port circuit with registers controlled by the address decoder for entry of address information from the data bus of the first computer and assertion of the address information on the address bus of the second computer.

Abstract: A method of resetting coupled modules and a system using the method are disclosed. The method comprises applying a reset instruction signal to a selected module, the selected module generating a reset permission request signal, one or more other modules (other than the selected module) receiving the reset permission request signal and taking necessary action to avoid system malfunction after the selected module is reset, the one or more other modules sending a permission granted signal, and resetting the selected module once it is determined that the one or more modules have sent a permission granted signal. Other methods and systems are disclosed.

Abstract: In order to compare the total reached by a counter counting pulses from a source with a given number, the more significant digits from the counter are compared with the corresponding digits of the given number. The comparator produces an output when the groups of more significant digits are equal. An adjusted output taking account of the less significant digits of the given number is obtained by delaying the output by a time period equal to that required for the number of pulses from the source to be incremented by the number represented by the less significant digits of the given number. The time delay is provided by a multi-stage shift register using the pulses from the source as shift pulses, the output from the comparator being applied to the first stage and the adjusted output being derived from a stage selected according to the less significant digits of the given number.

Abstract: There is disclosed a system and method for operating a memory controller in a manner which will allow memories with differing address sizes to be connected to a common bus. The controller decodes address information to change from a determined default address size to another address size on a dynamic basis during the actual memory access cycle. Upon detection of larger memory size, an adjustment occurs in the presentation of address information on the common address bus.

Abstract: A register circuit and method which allows a multi-bit register to change states until such time as a particular dedicated bit is activated. Once the dedicated bit is turned to the logical on-state none of the bits, including the dedicated bit, can be changed until a reset signal is sensed.

Abstract: A digital data storage circuit for a digital signal processor which is capable of receiving asynchronous inputs and is such as to be testable by selectively configuring the storage circuits as a shift register enabling the entry and extraction of test data into the processor. The storage circuit includes two latch elements each formed by two complementary transistor inverter circuits connected in a positive feedback arrangement and in which the output current capability of the second inverter circuit is restricted to enable the latch element to change state in response to input signals applied to it. Asynchronous inputs are applied to a first latch element through switch means comprising a complementary transistor inverter responsive to a SET input in series with a transistor responsive to a CLEAR input. The complementary inverter is connected to the input of the first latch element through a series connected transistor.

Abstract: In order to compare the total reached by a counter counting pulses from a source with a given number, the more significant digits from the counter are compared with the corresponding digits of the given number. The comparator produces an output when the groups of more significant digits are equal. An adjusted output taking account of the less significant digits of the given number is obtained by delaying the output by a time period equal to that required for the number of pulses from the source to be incremented by the number represented by the less significant digits of the given number. The time delay is provided by a multi-stage shift register using the pulses from the source as shift pulses, the output from the comparator being applied to the first stage and the adjusted output being derived from a stage selected according to the less significant digits of the given number.

Abstract: A digital data storage circuit for a digital signal processor which is capable of receiving asynchronous inputs and is such as to be testable by selectively configuring the storage circuits as a shift register enabling the entry and extraction of test data in the processor. The storage circuit includes two latch elements each formed by two complementary transistor inverter circuits connected in a positive feedback arrangement and in which the output current capability of the second inverter circuit is restricted to enable the latch element to change state in response to input signals applied to it. Asynchronous inputs are applied to a first latch element through switch means comprising a complementary transistor inverter responsive to a SET input in series with a transistor responsive to a CLEAR input. The complementary inverter is connected to the input of the first latch element through a series connected transistor.