International Business Machines Corporation

Johann Hajdu

Klaus J Getzlaff

Dieter Bazlen

Guenter Knauft

Dietrich W Bock

Herbert Chilinski

Wilhelm Ernst Haller

Arnold Blum

Hellmuth R Geng

Helmut Painke

Stephan R Richter

Udo Wille

Fritz Irro

Guenther Sonntag

Siegfried Neuber

Rolf Berger

Gunter Knauft

Birgit Withelm

Franz J Raeth

Claus Erich Mohr

Leopold Reichl

A computer system is described with a 32 bit arithmetic and logic unit which is coupled to a 64 bit data bus. A number of general purpose registers are provided which have 32 bits each and which are organized in two groups. Two 32 bit data words which are present on the data bus can be transmitted and stored in the two groups of the general purpose registers. From there, the two data words can be transmitted via two operand registers to the arithmetic and logic unit. Several further lines are provided for bypassing the general purpose registers and/or the arithmetic and logic unit, if desired. Due to the fact that two data words can always be transmitted, the performance of the computer system is enhanced.

Computer system with double width data bus

The invention relates to a multi-chip computersystem with master-slave latches. It is known to provide all latches on all chips with two clock pulses, respectively. With the help of the latches the digital signals are pipelined through the logic gates on the chip. Due to tolerances, the edges which control the masters and the slaves have a skew. According to the invention, one of the two clock pulses is generated on the chip itself, respectively, by ANDing an auxiliary clock pulse with the other of the two clock pulses. This has the result, that the above mentioned edges of the two clock pulses occur almost at the same time with the consequence that the frequency of the clock pulses can be increased.

Clock generation in a multi-chip computer system

A method of operating a timer mechanism in a digital data processing system is described in which the contents of at least one timer register is updated by a predetermined time increment during each of successive periodic update cycles. Each update cycle includes a predetermined number of operating cycles of the data processing system. During each update cycle, the contents of an adjustment register is circularly shifted by one bit position and if the bit value at a particular position in this adjustment register has a predetermined binary value during an update cycle, then actual updating of the timer register is omitted during a related update cycle.

Method of operating a timer in a digital data processing system

In the processing of instructions in data processing systems it is not always possible to execute these instructions without interruption since particular situations, in the following called events can occur which necessitate a short interruption for executing the operations caused by such events before continuing the interrupted instruction processing. Such repetition however is only possible when the contents of the operation register containing the instruction is frozen during the interruption. Such a situation requires two actions: the first is the execution of a forced operation to resolve the event. The second action is a repetition of the instruction and execution phase of the interrupted instruction.

Device in the instruction unit of a pipeline processor for instruction

In a microprogram-controlled processor, having an additional operating mode in which particular functions can be executed under direct hardware control, a mode latch signals whether microprogram instructions or directly controlled macro instructions are to be executed. The macroprogram instructions are conventionally executed. For the execution of directly controlled macro instructions, a control storage supplies a hardware control word associated with the macro instruction to be directly executed. The hardware control word contains a mode control bit for signalling that the direct hardware control mode is to be executed. The remainder of the hardware control word contains a plurality of direct control bits, each of which directly controls a hardware function. In an alternative embodiment multiple hardware control words are employed.

Macroinstruction execution in a microprogram-controlled processor

The cycle time of a data processing system should always be determined in such a manner that data from a source register, after having been propagated through, if necessary, several transfer sections and line drivers, and through a chain of logic circuits for the respective processing steps, can be stored in the result or sink register safely and even with the worst case propagation tolerance of all elements involved. The ideal cycle time therefore, which is dependent on the processing speed of the slowest chain of logic circuits, has to have added time segments for the worst case of unprecise clocking. A reduction of the cycle time by the above mentioned added time segments, and if necessary by the propagation delays in the transfer sections and in the line drivers, is achieved when the chain of logic circuits and thus its delay time is divided into two partial chains with the partial delays and if the sink register is arranged between the two partial chains. By thus splitting the chain of logic circuits into two partial chains, the logic partial functions can be executed during that time segment which is composed of the above mentioned added time segments.

Arrangement in a data processing system to reduce the cycle time

An improved data processor control subsystem in which a cycle counter having a plurality of cascade-connected stages also comprises one or more supplemental or dummy stages, which can be selectively inserted or removed from the chain of cascade-connected stages, to alter the number of sub-cycles in an operating cycle, thereby decreasing the complexity of associated decoding circuitry.

Data processor control subsystem

In executing and controlling internal data flow for a particular program, it is often necessary to delay execution of an instruction by the insertion of an appropriate number of wait cycles. Thus, it may be necessary to interrupt instruction execution, for example, to insert a given number of wait cycles for channel access to common storage of the data processing system, for reloading a data or instruction buffer, or for a like situation. In such cases, the control unit has to ignore the particular instruction awaiting execution and execute another forced operation instead. An appropriate code is provided for a NO OPERATION instruction, say all bits zero. When a forced operation is to be executed, this code can be generated with fewer logic means at the output of the instruction register. As a result, there are no control signals active at the output of the decoder. The signals indicating forced operations have to be considered by the decoder only if a control signal is to be generated. If the control signals need be grouped for physical reasons, it is possible to determine which of these signals are a function of forced operations. This will negate the need to otherwise distribute these control signals throughout the decoder, thereby reducing and simplifying the wiring required.

Control device for directing execution of forced operations in a data

An LSI integrated semiconductor circuit system comprised of a plurality of interconnected minimum replaceable units. The system and each minimum replaceable unit fully conforms to the Level Sensitive Scan Design (LSSD) Rules. [Level Sensitive Scan Design Rules are fully disclosed and defined in each of the following U.S. Pat. Nos. 3,783,254, 3,761,695, 3,784,907 and in the publication 'A Logic Design Structure For LSI Testability' by E. B. Eichelberger and T. W. Williams, 14th Design Automation Conference Proceedings, IEEE Computer Society, June 20-22, 1977, pages 462-467, New Orleans, La.]. Each of the minimum replaceable units includes a shift register segment having more than two shift register stages. Each register stage of each shift register segment of each minimum replaceable unit includes a master flip-flop (latch) and a slave flip-flop (latch). Connection means is provided for connecting the shift register segments of said minimum replaceable units into a single shift register. Additional controllable circuit means including test combinational circuit means is provided for setting a predetermined pattern in only said first two stages of each shift register segment of said minimum replaceable units. The additional circuit means facilitates and is utilized in testing the circuit integrity (stuck faults and continuity) of each minimum replaceable unit.

LSI Circuitry conforming to level sensitive scan design (LSSD) rules and

In a micro-controlled data handling system the number of lines and pins required to transfer control signals from the microprogram controls to be integrated circuit modules controlled by such signals is conserved by using two bussing paths for distributing the control signals to the modules. A first path is dedicated exclusively to pre-decoded control signal functions and a second path is shared for transferring both data and control signal functions. Each controlled module contains an additional decoding circuit for combinationally decoding control signal functions received through both paths.

Arrangement for micro instruction control

Input/output registers integrated with logic and arithmetic circuits are combined externally of a processor nucleus having only storage registers, instruction decode logic, timing circuitry and arithmetic and logic unit for executing microinstructions whereby the use of the input/output registers is determined by microprogram code and by time control to either selectively execute all adapter and interface communication and control functions for input and output devices or to selectively be switched into the data flow of the processor nucleus.

Processor nucleus combined with nucleus time controlled external

A parallel adder with sequential carry ripple is subdivided into sections. Detector circuits are distributed over the various digit positions of the adder. Each detector circuit receives the digit pairs of the input operands of at least one adder position. The detection circuits indicate the beginning or the end of a carry ripple chain by testing the condition 'both input digits zero or both input digits one'. Via a coder, the output signals of the detection circuits are combined in the form of group indicating signals, each of which corresponds to a predetermined distance between the digit positions. By means of the group indicating signals a clock circuit is controlled in such a manner that the operating time is limited to the time required for carry rippling.

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Boeblingen, Germany

Johann Hajdu