Abstract: The present invention is a computer operating system method for allowing applications running in Virtual Machines, including but not limited to DOS applications, making direct UART I/O accesses under Windows for Workgroups.TM. or Windows 95.TM. operating systems to access VCOMM port drivers installed in the system. The invention involves the steps of: (1) receiving from the application instructions for a UART; (2) simulating a UART by returning to the application simulations of the responses of a UART; (3) translating the instructions for a UART into instructions for VCOMM; (4) sending the translated instructions to VCOMM; receiving responses from VCOMM; (5) translating the responses from VCOMM intosimulated responses from a UART; and (6) transmitting the simulated responses from a UART to the application.

Abstract: A servo controlled actuator for an automated liquid dispenser for dispensing reagents or diluting samples with reagent automatically in accord with a programmed local microprocessor or remote computer control. The dispenser has at least one reciprocable syringe, valving for it and a syringe actuator driven by a hybrid servo control. The actuator includes a bi-directional variable speed motor and an encoder developing a pulse train which in number is representative of the position of the syringe piston and in repetition rate is representative of piston velocity. A microprocessor controls the piston stroke from the pulse train by comparison to a memory-stored count and controls piston velocity in predetermined relation to the terminal end of piston travel.