| 摘要 |
A method and apparatus for performing overlapping service of requests to two peripheral devices, specifically a CD-ROM drive and a hard disk drive connected to a computer. When a read request is issued to the CD-ROM drive, a seek is immediately initiated. A timer, with a period much shorter than the typical seek time of a CD-ROM drive, is started and any requests to the peripheral hard disk drive are initiated. When the timer times out and when the hard disk request is complete, an inquiry is made to determine whether the CD-ROM drive has finished seeking. This inquiry is accomplished by determining the status of a bit set by the CD-ROM drive in a register in the computer when the CD-ROM drive has finished seeking. If the bit is set, indicating the CD-ROM seek is complete, the data transfer request is immediately issued to the CD-ROM drive. If the bit is not set, indicating the CD-ROM seek is not complete, the timer is reset and the service of hard disk drive requests continues.
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