Control Diagnostic Registers; Alternate Status Register; Device Control Register; Digital Input Register - Maxtor DIAMONDMAXTMPLUS6800 90683U2 Product Manual

Control Diagnostic Registers

These I/O port addresses reference three Control/Diagnostic registers:

Alternate Status Register

Contains the same information as the Status register in the Task File. However, this register may be read at
any time without clearing a pending interrupt.

Device Control Register

Contains the software Reset and Enable bit to enable interrupt requests to the host. Bit definitions follow:
Reset – Setting the software Reset bit holds the drive in the reset state. Clearing the bit re-enables the drive.
The software Reset bit must be held active for a minimum of 5 µsec.
IRQ Enable – Setting the Interrupt Request Enable to 0 enables the IRQ 14 signal to the host. When this bit is set
to 1, IRQ14 is tri-stated, and interrupts to the host are disabled. Any pending interrupt occurs when the bit is set to 0.
The default state of this bit after power up is 0 (interrupt enabled).

Digital Input Register

Contains information about the state of the drive. Bit definitions follow:
Bit 7 of the host data bus is not driven when this register is read.
-Write Gate – Reflects the state of the active low write gate signal on the drive.
-Head Select 3 through -Head Select 0 – Represents the ones complement of the currently selected head number.
-Drive Select 1 – Is 0 if drive 1 selected; 1 otherwise.
-Drive Select 0 – Is 0 if drive 0 selected; 1 otherwise.
HOST SOFTWARE INTERFACE
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