Non Polled Service Request Identification Method and Apparatus for Magnetic Disk Drives
Original Publication Date: 1980-Jul-01
Included in the Prior Art Database: 2005-Feb-13
A series of magnetic disk drives, such as drives X, Y and Z, are effective individually to make electrical contact with adapter 8 driven by CPU 10, or adapter 8 is effective to make contact with a selected one of the drives X, Y and Z. If adapter 8 makes contact with the drive, adapter 8 lowers the signal level on the appropriate ADDRESS line in bus 12, such as ADDRESS line x for drive X, connected through jumper 13x to interface 14x, and adapter 8 then pulses DRIVE SELECT line 16 connected to interface 14x so that DRIVE SELECTED signal on line 28x rises. The drive, such as drive X, is then selected. In the other case in which a drive wishes service, drive Z, for example, the drive requiring service raises its SERVICE REQUEST signal as on line 24z.