RK06/RK07 Disk Drive User's Manual - Trailing-Edge

Start Spindle Command
If a Start Spindle command is initiated for a drive in which the heads have already been loaded, a
controller interrupt can be returned on completion of the command, but an attention interrupt cannot
be returned.
Unload Command
If an Unload command is initiated for a drive in which the heads have already been unloaded, a
controller interrupt can be returned on completion of the command; but an attention interrupt cannot
be returned.
Drive Error Unload/Reload
When a drive is in the RUN state and the heads unload due to a drive error (refer to Paragraph 7.2.6,
Current Drive Attention - Bit 14), a successful error clear will result in a reload of the heads and the
generation of two interrupts: the first interrupt will occur with the drive error, and the second interrupt
will occur (up to 6 seconds later) when the heads reload.
Enabling an Interrupt
The Interrupt Enable (IE) bit (bit 6 in RKCS 1) must be set prior to the initiation of an operation or an
interrupt will not be generated.
Simultaneous Interrupts
If interrupt conditions simultaneously occur in the controller due to the overlapping of an operational
and data transfer command (e.g., Seek done and Read Data done), the data transfer interrupt will take
precedence and the operational interrupt will not be processed until another operation is completed.
Therefore, to ensure that no interrupts are lost, a program should scan all interrupt indIcators in
conjunction with the recognition of an interrupt.
Drive Ready Requirement
A Seek, or any other head motion command, will be ignored by a drive if the Drive Ready (DRDY) bit
is not asserted in the RKDS register when the command is initiated.
Dual-Access Operation
The programmer should be aware of a problem that can occur only with the Dual-Access Option. See
Paragraph 9.4.3.
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