Abstract: An efficient, cycle-accurate processor execution simulator models a target processor by executing a program execution image comprising instructions having run-time dependencies resolved by execution on an existing processor compatible with the target processor. The instructions may have been executed upon a processor in an I/O environment too complex to model. In one embodiment, the simulator executes instructions that were directly executed on a processor. In another embodiment, a markup engine alters a compiled program image, with reference to instructions executed on a processor, to remove run-time dependencies. The marked up program image is then executed by the simulator. The processor execution simulator includes an update engine operative to cycle-accurately simulate instruction execution, and a communication engine operative to model each communication bus of the target processor.

Abstract: A processor simulation environment includes a processor execution model operative to simulate the execution of processor instructions according to the characteristics of a target processor, and branch override logic. When the processor execution model decodes a branch instruction, it requests a branch directive from the branch override logic. In response to the request, the branch override logic provides a branch directive that resolves the branch evaluation. The request may include a branch instruction address. The branch override logic may index an execution trace of instructions executed on a processor compatible with the target processor, using the branch instruction address. The branch directive may include an override branch target address, which may be obtained from the instruction trace, or otherwise calculated by the branch override logic. In this manner, accurate program execution order may be simulated in a simulation environment in which complex I/O is not modeled.

Abstract: A communication network implements a timing system that closely approximates network response times so that information may be transmitted between two data processing systems within the network in a timely and efficient manner. During operation of the communication network, a sending data processing system sends query data to a receiving data processing system. A response timer within the sending data processing system is initialized to track the query operation. If the receiving data processing system provides a response to the sending data processing system before the response timer expires, the timing implemented for data communications is proper for the communication network. However, if the receiving data processing system fails to provide a response within a time specified by the response timer, the transmitting data processing system resends a query frame.

Abstract: A system and method for updating software for a remote unit over a network is disclosed herein. The system and method includes the remote unit, an authentication server and an update server. The remote unit may have a flasher host for communicating over the network and for transmitting commands to the remote unit. The system and method allows for the verification of a request message from the remote unit, and a response from the authentication server. The response message to the remote unit from the authentication server will contain an decryption key to decrypt the update file that will be sent by the update server. Such an authentication process prevents rogue programs from being sent to the remote unit thereby decreasing the potential for cellular fraud.

Abstract: A token ring network performs address to port mapping by taking advantage of the abilities of the port switched modules and the neighbor notification process, in order to perform address to port mapping on each individual module. Ring monitors are switched from an upstream side of a port to a downstream side of a port when the neighbor notification process enters the port domain. The processor on the module records all the addresses received on the downstream side of the port, when the neighbor notification process is in the domain of that port. If it appears that the neighbor notification process is in the domain of two adjacent ports, the present invention only records addresses from the most downstream of the two adjacent ports, since such a situation is an indication that the upstream ports do not conform to MAC protocol.