Abstract: Tests are performed prior to or during the boot operation to determine whether files are corrupted. This may indicate the presence of a virus. If a potential error is detected, boot is halted, allowing the user to boot from uncorrupted files. In another embodiment, an uniquely formatted floppy diskette is used as an access diskette serves as a hardware key to gain access. In another embodiment, a host controls information stored locally. In another embodiment, security from unauthorized access is provided once a valid user has legitimately accessed a computer. In response to a predefined hot key or a predetermined period of time during which the user has not provided input, portions of the computer are disabled. Upon entry of access information by the valid user, the disabled features are enabled. In another embodiment, access to the computer is made more difficult in response to invalid access attempts.

Abstract: Expandable data modem for data transmission of digital data at certain defined data rates which includes a base for mounting those components of the modem which are data-rate independent and a sub-base for mounting all data-rate-dependent components, and a two-part plug-in connector for detachably plugging the sub-base into the base. In this way the modem can be expanded to higher data rates by simply replacing the sub-base with its data rate-dependent components instead of replacing the entire modem. In a preferred embodiment the base and the sub-base are two printed circuit boards joined by a card-edge connector.

Abstract: A communications unit for an executive workstation which provides a switching arrangement for interconnecting voice and data lines with a computer and a telephone instrument. The communications unit contains a microcomputer with memory which provides connection patterns and number directory for quick access to individuals and data services required by the user. In the preferred embodiment, the communications unit is configured as a printed circuit board that may be plugged into a desktop computer for direct access to the computer's keyboard and CRT monitor so that the user may use the keyboard and the monitor for all communications. The communications unit also is capable of connecting to a keysystem.