Abstract: A simulator for a digital system comprises a simulation model, an event queue for scheduling changes to the state of the simulation model at specified times, and a separate delta queue, for scheduling changes to the state of the simulation model that are to take place instantaneously. The use of separate event and delta queues facilitates optimization of the queuing. The simulation model comprises a number of replaceable parts, each of which contains and is responsible for managing its own state information. The event and delta queues contain references to the parts of the model for which changes of state are scheduled, without containing the actual values of those changes of state.

Abstract: A computer kiosk comprises a desktop with a main cabinet located under the desktop. A display unit is set into an aperture in the desktop. A pair of pockets, is set into the desktop, one on each side of the display unit, for holding peripheral devices. A pair of bins is mounted under the desktop, adjacent to the pockets, for holding electronic circuits associated with the peripheral devices. This provides a flexible configuration for the kiosk. The main cabinet may be positioned between the bins, with the display unit housed in the main cabinet, or else the main cabinet may be positioned to one side of the bins, with the display unit housed in a separate cabinet positioned between the bins.

Abstract: A computer has a memory storing a number of software applications, and a registration file, indicating which application versions are currently installed in the memory. A software update mechanism in the computer accesses a remote file server to obtain a release file containing a list of software applications available from the remote server, and compares the release file with the registration file to determine which of the installed applications have upgrades available. When a user selects an application for upgrading, and the update mechanism accesses the remote file server to obtain a manifest file containing details of the application files required to form an updated version of this applications. The manifest file is used to determine which of the required application files are already available in the computer; and only those application files that are not already available in the computer are accessed and installed in the memory.

Abstract: A copy protection mechanism for protecting software against copying, consists of a challenge mechanism embedded in each protected item of software. The challenge mechanism has no access to the customer's private keying material. In operation, the challenge mechanism sends a random challenge to the customer's signature server. The signature server signs the challenge, using the customer's private keying material and then returns the signed challenge to the challenge mechanism. The challenge mechanism then verifies the signed challenge, using the customer's public keying material, and prohibits the customer from using some or all of the protected item of software unless the verification is successful. The mechanism permits every customer to receive an identical copy of the copy protected program with the embedded challenge mechanism.

Abstract: A system including a personal computer (1) and a display (2) is usable by at least two persons (owner 3 and customer 5) in connection with an application which does not support multiple mice or multiple cursor presentations. Each person has a respective mouse (4,6) and the customer is permitted to participate in the operation of the application, at least to the extent of being able to point to objects on the screen by means of a cursor, rather than having to point with a finger etc or communicate verbally. This is achieved, without needing to modify the application, such as by loading appropriate mouse driver software into the personal computer in order to generate an auxiliary cursor for the customer, or using appropriate mice hardware/firmware/software, so that the customer's mouse can control the owner's cursor when required.

Abstract: A multi-processor system has a number of processing elements interconnected by a network for transmitting data frames between the elements. Each element includes an application layer, a transport layer and a link layer. The application layer contains end-point processes each having an address space. The transport layer can allocate a buffer in the address space of a specified end-point process and return details of the buffer to the link layer. The link layer can write message data from a received data frame directly into the allocated buffer by direct memory access without buffering the message data in the link layer. In this way, copying is reduced, improving the efficiency of the system.

Abstract: Arbitration apparatus is described for arbitrating between a number of jobs, for example for distributing message traffic over a data transmission network. The arbitration apparatus comprises an activity register containing a number of activity bits indicating which of a number of transmission jobs is currently active. The apparatus also includes a two-tier token ring arrangement comprising an outer ring and a number of inner rings. Each ring consists of a number of registers, holding a token which is passed cyclically around the ring. Each register has a bypass path which bypasses the register if a corresponding job or group of jobs is inactive. The positions of the tokens in the rings determines which job is to be scheduled next. Each ring also includes a keeper register for preserving the token if all the jobs are inactive.

Abstract: A mechanism is described for transferring data between a pair of relational databases on client and server machines. A client component creates a first pipe in the client, and sends information to a server component, enabling it to create a second pipe in the server. The client component then calls the data unloading utility of the client database, causing it to start to unload the data into the first pipe. The client component then starts up a Send process in the client, which reads data from the first pipe and sends it to the server. At the server, the server component calls the loading utility of the server database, specifying the second pipe as input. As the data arrives at the server, the server component writes it into the second pipe, from where it will be read by the loading utility and written into the server database.

Abstract: A parallel query manager accepts a list of file extents to be searched and produces a number of search lists, one for each disk to be searched. The query manager first uses a mapper to find out how the database spaces are stored on disk. It then matches the search extent list with the mapping information to determine which parts of which disks are to be searched. It then initiates several searches in parallel so that all the affected disks can be kept busy at the same time. The query manager then checks for return data on each stream, and merges the results.

Abstract: A flip chip is soldered to an array of flexible pillars of compliant dielectric material on a circuit board. Each pillar has an electrically conductive core electrically coupled to the circuit board. The pillars absorb movement due to differences in the coefficient of thermal expansion of the chip and board, and hence reduce the possibility of fatigue failure of the solder joint. The pillars are manufactured by forming a layer of compliant dielectric material on the circuit board, forming blind holes in the layer, filling the holes with electrically conductive material overlapping the edges of the holes, and then laser ablating to remove the compliant dielectric material except where protected by the electrically conductive material.

Abstract: A combined data and power transmission arrangement has one or more power supplies and loads interconnected by a power transmission line, with transmitters and receivers for transmitting a digital data signal over the transmission line. The transmitter and receiver each include an inductor for providing a high impedance barrier to a data signal on the line, so as to isolate the data signal from the power supply and load. The receiver includes circuits for tracking the mid-point value of the data signal to produce a threshold value, and for comparing the threshold value with the data signal to produce an output signal. The threshold value is a controlled positive feedback signal derived from the output of the comparator by way of a positive feedback loop having a time constant approximately equal to the time constant of the transmitter.

Abstract: A video-on-demand (VoD) system comprises at least one server and a number of subscriber units connected to the server by way of a network (e.g. an ATM network). The server comprises a processing unit, data storage means for storing video data, and service supply means for responding to requests from subscribers by dispatching sequences of video data from said storage means over the network to said subscribers. The service supply means comprises a video application running in user space in the processing unit, and a VoD kernel I/O driver (VKID) running in kernel space in the processing unit, for reading data from said data storage means and dispatching the data to said network, in response to commands from the video application. Because the VKID is a kernel level module, it can perform this transfer quickly and efficiently, without the overhead of copying the data to and from user space.

Abstract: A data processing element comprises at least one processor, a main memory, and a network coupler for coupling the processing element to a network. The network coupler includes a packing circuit for assembling the data frames into intermediate units of data, referred to as parcels, and a network coupler processor for assembling the parcels into datagrams in the main memory. Thus, the packing circuit relieves the network coupler processor of a substantial amount of low-level processing work.

Abstract: A database system holds data in the form of a sequence of records, each record comprising one or more fields. The database can be interrogated by a search query, which specifies a particular logical combination of comparisons to be performed on specified fields of each record. Before the search commences, the search query is compiled to produce an optimized sequence of code for search within a record. Each comparison operation is assigned a cost, reflecting the cost in time to retrieve the required fields and to perform the comparisons, and is also assigned a probability, indicating the probability that the comparison will produce a true result. Each logical operation in the search query is then processed, to find the order of handling its arguments that gives the minimum expected cost, and the arguments are re-arranged into that order.

Abstract: A data processing system has at least one processing module containing one or more blocks of memory, having control registers which are accessible via a diagnostic interface, and a clock module which distributes system clocks to the processing module(s), the operation of which is controllable using a similar diagnostic interface. One of the possible actions in the clock module is the generation of a single-shot clock pulse. A diagnostic control unit is connected to the separate diagnostic interfaces of the processing module(s) and the clock module, and is capable of simultaneously controlling the two diagnostic interfaces in such a way that a single-shot clock pulse can be synchronized with the diagnostic access to a processing module to effect the loading or dumping of a block of memory line by line.

Abstract: A data processing system comprises a number of processing nodes interconnected by a data transmission network. The network is "hairpin" shaped, having a first leg, a second leg, and a loopback connection connecting the first leg to the second leg. Each node sends public write messages on to the first leg, and receives messages from the second leg. All the messages flow through the loopback connection, which thus serves as a central chronology point for the system, defining a unique chronological order for the messages. The network can be reconfigured, to split it into a number of sub-networks, each with first and second legs interconnected by a loopback connection. The system may include a backup node, for disaster recovery, situated at a very long distance from the processing nodes.

Abstract: Apparatus is described for realigning a sequence of data bytes, such as a received datagram. The data is initially written into a multi-lane FIFO buffer, with the data in each lane pre-skewed by a controllable amount, determined by the address of the buffer area into which the data is to be transferred. The data is then read out of the FIFO buffer through a lane changer which rotates the order of the lanes by a controllable amount, also determined by the address of the buffer area. The apparatus can be used, for example, to realign data to ensure that the data is correctly aligned with cache line boundaries.

Abstract: A multi-processor system has a plurality of processing elements interconnected by a network for transmitting data between the elements. Each of the elements has a status table, indicating that element's view of the statuses of all the elements in the system, and a reliability map, containing a bit for each element in the system, along with copies of the reliability maps of all the other elements in the system. Each element sets the bits in its reliability map to indicate which of the other elements it is in regular communication with. Whenever an element's own reliability map changes, the element sends a copy of that map to all the other elements. Whenever any bit changes in any of the reliability maps held by an element, that element uses the maps to perform a status re-evaluation of all the elements, and updates its status table. This provides a consensus voting mechanism which ensures that all elements arrive at the same view of the element statuses.

Abstract: A computer system comprises at least one genetic optimization agent holding a pool of genotypes, representing possible solutions to a problem. The genetic optimization agent generates new genotypes from the pool, evaluates the new genotypes according to predetermined fitness criteria, and selects the fittest of the genotypes to form a new generation of genotypes in the pool. The system also includes a number of further agents, for generating further solutions to the problem, using different techniques, such as simulated annealing, constraint logic, and neural networks. These further solutions are also represented by genotypes. The genetic optimization agent imports genotypes from the further agents and adds them to its pool of genotypes for breeding and selection. The genetic optimization agent thus provides a way of integrating a number of different problem-solving agents, in such a way as to achieve synergy between them.

Abstract: An electronic identification system e.g. for identifying goods in a retail store, comprises an interrogator and a number of transponders. Each transponder includes a number of data registers, and a counter for selecting the registers one at a time in sequence. When the transponder receives an interrogation signal from the interrogator, it returns a response signal containing data from the currently selected register. When the transponder receives a switch signal from the interrogator, it steps the counter on to select the next register in the sequence. One of the bits in the selected register may be used as a mode switching bit, for switching the response signal between a normal power level and a reduced power level.