Digital Equipment Corporation

Other

Phoenix Technologies Ltd.

Massachusetts Computer Corporation

David A Cane

Paul Binder

David S Hirschman

John M Gunther

Stephen R Shalom

David Robert Dutton

A method and system for protecting computer program distribution within a broadcast medium involves encrypting at least a portion of the computer program S.sub.i using an encryption scheme keyed to both an encryption key SK.sub.i and a program identifier i. Each decryption device (PCDD) also has an associated identifier j. Two tables are generated and stored in a memory device: a first table, including correlations between the encryption key SK.sub.i and the program identifier i; and a second table, including correlations between the password key PK.sub.j and the hardware identifier j. A password P.sub.ij is generated based on both the encryption key SK.sub.i and a password key PK.sub.i is retrieved from these tables. The password P.sub.ij is transmitted to the user for subsequent use in decrypting the subject software program contained on the medium.

Software catalog encoding method and system

An improved amusement device includes a base and open-top guide tube with two or more balls in the tube. When the balls are lifted to the top of the guide tube and dropped, the top ball rebounds to a height much higher than that from which it was dropped. With three balls in the tube, for example, the top one will typically rebound to a height six times as high as the height from which it was dropped.

Bouncing ball launcher

According to the present invention, a telephone answering machine stores a plurality of messages and establishes a correspondence between those messages and a plurality of phone numbers. The phone number of a caller is identified and one of the plurality of messages selected for playback based on the identified phone number and the established correspondence. In a preferred embodiment, the answering machine is microprocessor-based and the correspondence of telephone numbers to messages is stored in a memory table. Messages may be stored either on magnetic media or in semiconductor memory using a signal compression/decompression module where economy dictates in order to reduce the size of the semiconductor memory. Microprocessor control allows economical realization of a full-featured machine.

Multiple message answering machine keyed to the incoming phone number

A computer memory control capable of controlling a virtual memory system and optimized for handling multi-tasking or multi-processing systems is disclosed. In operation, each task or process is assigned a unique process number. The memory control circuitry which translates a virtual address produced by the system processor into a physical address suitable for memory access includes a unique translation buffer store each entry of which comprises a physical address, the usual tag bits and the process number of the process utilizing that address. During an address translation, buffer store entries are indexed using the virtual address used by the processor. In addition to the usual tag bit comparison to verify data validity, a comparison is made between the process number of the process presently running and the process number stored at the indexed buffer entry. The translation is considered successful only if both the tag bits and the process numbers match. With this arrangement each process is effectively assigned a unique address space in the translation buffer and translations reside in the buffer simultaneously for all running processes. In order to prevent continual overwriting of the translation buffer entries when a plurality of short programs are running simultaneously, an offset number, uniquely associated with each process, is added to a portion of the virtual address prior to indexing the translation buffer store in order to physically separate the address space for each process from other address spaces which are simultaneously in the buffer.

Computer memory control

A data processing system including a plurality of data units and a common bus. The data unit includes apparatus for issuing instructions including a LOCK instruction and an UNLOCK instruction. Each data unit includes apparatus responsive to the instructions such that, if the first data unit issues a LOCK instruction, the data unit other than the first data unit, are prevented from transferring information over the common bus with a LOCK instruction until an UNLOCK instruction is issued by any data unit.

Data processing system with lock-unlock instruction facility

A data processing system in which a unit needing to be serviced by a processor first requests an interrupt and, after the interrupt is granted by the processor, requests access to a system bus to transfer interrupt information as it normally would transfer other information. The interrupting unit must wait for other units having higher priority to transfer information, usually memory information over the bus, before it can access the bus to transfer its interrupting information. This permits transfers of information having higher priority to occur before the transfer of the interrupt information is transferred.

System for interrupt arbitration

When two asynchronous signals may occur at approximately the same time, only one of the signals being able to control consequent events, a circuit accounts for the conflict situation by selectively adding a delay until the conflict situation has settled. While the circuit does not determine which asynchronous event may control, the selective delay extends the time for the decision to be made. This circuit provides high reliability while minimizing delays and eliminates the need for indiscriminately adding a delay to each asynchronous event so as to resolve conflict situations. The circuit has particular applicability to volatile memory systems wherein conflict between processor requests and refresh requests to memory occur and allows processor requests to proceed with minimum delay in nearly all situations.

Growing community of inventors

Sudbury, MA, United States of America

David A Cane