Abstract: A personal computer subsystem, having a hardware module and protection software, is designed to protect files on a personal computer from inadvertent or intentional distortion, and can be used to protect personal computers from programs known as computer viruses. The hardware module is connected to the personal computer system busses and the software has a kernel which ensures the security of one access path to the hard disk controller and utilizes the above-mentioned module to block other access paths to the hard disk controller. The only permitted access path to the hard disk controller is a path which uses the computer's operating system, modular device driver and basic input/output system. All other access paths to the hard disk controller are interpreted by the personal computer subsystem as forbidden.

Abstract: A centrifugal pump is proposed for handling liquids carrying solid abrasive particles in a casing having a flow-through portion formed by a discharge passage and a flow-through passage of an impeller accommodated inside the casing. The discharge passage is confined by a front and rear wall of the casing, relative to the incoming flow of the liquid being transferred, and by a peripheral wall of the casing integral with the front and rear walls. The geometry of the peripheral wall of the casing follows the pattern of the distribution of the solid abrasive particles in the flow-through portion of the pump. The flow-through passage is formed by a carrying disk mounted on a drive shaft and having vanes secured thereto, and by a driven disk secured on the vanes.