Address Vector Protection From BASICA Exits for PC Asynchronous Communication Card
Original Publication Date: 1985-Mar-01
Included in the Prior Art Database: 2005-Feb-18
A software procedure is described to detect and recover from errors in the asynchronous communication card of the IBM Personal Computer (PC) caused by exits from PC BASICA programs and other errors generated by applications that modify address vectors. A printer driver program uses the asynchronous communication port to communicate with the printer connected to the PC. When a BASICA application program is exited, the true status of the asynchronous communication card is altered and resident programs can no longer control the card functions. Data synchronization is lost between the printer and the printer driver. The new software routine provides detection and recovery from modifications to the address vectors or status which occur when a BASICA application program exits.