Software Polling Algorithm With Timeout Protection
Original Publication Date: 1989-Jul-01
Included in the Prior Art Database: 2005-Jan-28
In processing data on a diskette, data transfer with the diskette controller must occur at a specified rate or the operation will fail with an overrun error. The operation may be either a write operation or a read operation. In most of the IBM Personal Computer family of products, the data rate is sustained by the use of direct memory access (DMA) whenever it needs to process data. However, in the IBM PCjr and the Wheelwriter Series II Diskette Option, DMA capability is not provided. Without DMA, the software must poll the diskette controller whenever data transfer is expected. A problem arises with the non-DMA method. The diskette controller may start a command but never transfer (Image Omitted) any data and thus never finish.