International Business Machines Corporation

Guenter Knauft

Johann Hajdu

Klaus J Getzlaff

Arnold Blum

Ulrich Weiss

Dietmar Schmunkamp

Stephan R Richter

Bernd Leppla

Fritz Irro

Hermann Schulze-Schoelling

Hellmuth R Geng

Horst Von Der Heyden

An electrical circuit for generating clock pulses for a multi-chip computer system which contains a clock generation chip and various logic circuit chips. The clock pulses used on the logic circuit chips are generated on the clock generation chip and are transferred to the logic circuit chips. For the generation of the clock pulses a so-called clock splitter circuit is provided on the clock generation circuit. This clock splitter generates two pulse strings out of a third pulse string which is derived from an oscillator. The clock splitter contains a number of gates and latches which have an impact on the throughput time of a pulse to run through the clock splitter, as well as on the skew of the two generated pulse strings. The invention provides an electrical circuit which has an improved throughput time and skew of the generated pulse strings.

Electrical circuit for generating pulse strings

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

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

A method for performing manual operations, such as address compare equal stop, single cycle alter, etc., in a time slice controlled microprocessor with microprogramming, which avoids stopping the processor clock when any of the programs requires a manual operation. This problem is solved by assigning the manual operations to a specific program, which for the other programs in the multiprogram environment executes the manual operations required.

Method of implementing manual operations

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.

Growing community of inventors

Boeblingen, Germany

Guenter Knauft