| 摘要 |
<p>A computer connected to a telecommunication network via a modem is isolated from the network by a second computer, which acts as a buffer for the receipt and transmission of data and prevents unauthorised access. The second computer may include two drives either on the same hard disc or on separate hard discs. One drive serves as a buffer store for outgoing messages and the other for data received from the telecommunications network. A software or hardware interlock may be provided to prevent simultaneous connection of the two drives to a common computer bus. The second computer may be constructed from one or more expansion cards, fitted inside the first computer. The second computer is such that no connection is provided between the first computer and modem except through an inlet/outlet port on the expansion card and no direct path can be established on the expansion card between the modem inlet/outlet port and the main computer bus. The arrangement is useful with e-mail and communications on the Internet and may use security mechanisms including passwords, virus checks and caller identification.</p> |
