Amdahl Corporation

Stephen S Si

Eugene T Wang

Stephen J Rawlinson

Hsiao-Peng S Lee

Gary A Woffinden

Jongwen Chiou

Daryl H Allred

James B Shackleford

Dale F Merrick

Greg Aldrich

H P Lee

Gregory Aldrich

A clock distribution system for reducing clock skew between tightly coupled central processing units in a multi-processor system. The multi-processor system includes (1) a configuration processor for generating a first configuration signal and a second configuration signal, a first clock, a second clock, (2) a first processor having a first central processing unit, (3) a second processor having a second central processing unit, (4) a first clock generator for generating a first delayed clock signal from the first or second clock in accordance with the configuration signals, and (6) a second clock generator generating a second delayed clock signal from the first or second clock in accordance with said configuration signals. The clock distribution system comprises a distribution means for receiving the first delayed clock signal, the second delayed clock signal and the configuration signals, and for distributing in accordance with the configuration signals either the first delayed clock to the first central processing unit and the second delayed clock to the second central processing unit, or the first delayed clock signal to both the first and second central processing unit or the second delayed clock signal to both the first and second central processing unit.

Clock distribution system for reducing clock skew between processors in

A selectable timing delay system which provides for delaying an input signal a specified length of time within a specified tolerance wherein the range and resolution of the selectable timing delay system are so specified that the selected delay within the selected tolerance is obtainable regardless of the relative speed of the integrated circuit chips used in forming the selectable timing delay system.

Selectable timing delay system

A circuit responsive to a switching signal for dynamically changing the frequency source of a system clock. The circuit allows addition of new frequency sources without substantial changes to the circuit because its circuitry for detecting an inactive cycle period of the new frequency source is asynchronous (i.e. not clocked by the new frequency source).

Apparatus for synchronously switching frequency source

A clock control apparatus that stops a system clock in a high performance high speed computer a determined number of system clock cycles after the generation of the clock control signal by a digital computer. The apparatus receives a basic clock signal and the clock control signal and generates a system clock for the system. The system clock includes a normal system clock signal and at least one early system clock signal. The basic clock is provided through a delay tap generating a normal basic clock signal and at least one early basic clock signal. In addition, a control state machine receiving the normal basic clock signal and the at least one early basic clock signal and responsive to the clock control signal is provided for starting and stopping the system clock. The clock control signal is synchronized with the earliest system clock and supplied to the clock control state machine.

Deterministic clock control apparatus for a data processing system

Disclosed is a scan apparatus which provides an interface and control signals between a secondary computer and data locations in a host computer. The scan apparatus functions independently of the normal operation of the host computer. Scan-out is performed transparently to the operation of the host computer. The host computer is organized into a plurality of functional units. Each functional unit is constructed of circuits on semiconductor chips. The semiconductor chips are organized in blocks. In the present invention, each block within the host computer includes a multimode scan apparatus which controls the scan operations in connection with that block. The scan apparatus in each block is connected to the secondary computer by clock and scan lines. The scan apparatus on each block includes a multimode sequencer which is controlled by the secondary computer and independently of the operation of the host computer, executes the scan sequences for performing the scan operations associated with the block.

Multimode scan apparatus

Data processing apparatus includes a data path having a path delay, from a source latch point to a destination latch point, of greater than one clock cycle. For an n-cycle path, where the path delay is between n- 1 and n clock cycles, data is latched into the source latch point at least n clock cycles in advance of the cycle on which it is needed at the destination latch point. The data and gating signals along the data path are held glitch-free in the source latch point until after the clock cycle on which the data is used in the destination latch point.

Saving registers in data processing apparatus

In a floating point arithmetic unit, high speed computation is achieved by providing logic for determining whether operands of an instruction have a predetermined condition with respect to the instruction and logic responsive thereto for bypassing selective primitive operations when such predetermined condition exists.

High speed floating-point unit

An instruction execution unit receives instructions and, in turn, provides a sequence of control words to specify the sequential processing of the operand data provided with the instruction. A sequencer nominally issues a first sequence of control words corresponding to the instruction. The sequencer includes a sequence selector for selecting a second sequence of control words for issuance by the sequencer. Control logic is provided to determine from the operand data, concurrent with the issuance of at least the first issued control word, whether the operand data is ideal with respect to the instruction, where ideal is defined as the predicted nonoccurence of underflow and overflow conditions. On determining that the operand data is ideal with respect to the instruction, the sequence selector is caused to select the second sequence of control words for issuance.

Pipelined data processing system utilizing ideal floating point

A scan apparatus provides an interface and control signals between a secondary computer and data locations in a host computer. The scan apparatus functions independently of the normal operation of the host computer. Scan-out is performed transparently to the operation of the host computer. The host computer is constructed using circuits on semiconductor chips. The semiconductor chips are organized in blocks. Chips within each block include scan apparatus which controls the scan operations in connection with that chip. The scan apparatus in each chip is connected through two I/O pins to a clock line and to a bidirectional scan data line. The scan apparatus on each chip includes a multimode sequencer so that each chip in each block can be independently performing scan sequences. The block scan apparatus and the secondary computer perform the functions of requesting a scan sequence for transmitting the scan data.

Integrated circuit scanning apparatus having scanning data lines for

An ancillary execution unit is interfaced to a primary execution unit of a data processing system where the ancillary unit operates faster than the primary for certain instructions and allows for bypassing the slower unit. The primary execution unit has an instruction input receiving an instruction, an operand input receiving data and an operand output transferring data from the primary execution unit to the data processing system. The ancillary execution unit obtains the instruction from the instruction input, obtains the data from the operand input, performs the function indicated by the instruction to the data, and returns data to the primary execution unit.

Ancillary execution unit for a pipelined data processing system

A two control store scheme with instruction execution overlay is shown in a data processing system execution unit having a two-state pipeline. The first control store controls the first-stage facilities during the first cycle of instruction execution and points to the initial location of the second control store. The second control store controls the second-state facilities during the final cycle of instruction execution. The second control store also controls the facilities of both stages during the intermeidate cycles of instruction requiring more than two cycles to execute. Because the second control store controls only the second-stage facilities during the final cycle, execution of the first cycle of the following instruction can take place concurrently within the first-stage facilities under the control of the first control store.

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Milpitas, CA, United States of America

Stephen S Si