METHOD AND SYSTEM FOR SIMULATED MULTI-TASKING

A computer-implemented method and apparatus for servicing multiple external interfaces in a pseudo-parallel fashion which simulates multi-tasking. An application program is programmed to switch control during the servicing of multiple external units and/or time-consuming CPU steps to optimize overall application execution time. An application services each of these external interface units through calls to respective program modules. Relatively long program modules contain calls to transfer system control to shorter program modules which await servicing. These calls are strategically inserted in a long program module after one or more partial logic of units of work have been completed. At the time of each call, a check is first made to determine whether servicing of another external interface unit with a short program module is required. If servicing is required, then control is transferred to execute the short program module. Switches between servicing the multiple external interfaces, such as a user-interface and a communication link, are substantially transparent to external users. Sub-second responses are provided simulating multi-tasking of the communication interface and the user-interface during execution of an application by a personal computer.