Control Diagnostic Registers; Alternate Status Register; Device Control Register; Digital Input Register - Maxtor 4W100H6 Product Manual

Control Diagnostic Registers

Control Diagnostic Registers Control Diagnostic Registers Control Diagnostic Registers Control Diagnostic Registers
These I/O port addresses reference three Control/Diagnostic registers:
I/O POR T R EAD

Alternate Status Register

Alternate Status Register Alternate Status Register Alternate Status Register 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

Device Control Register
Device Control Register Device Control Register 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

Digital Input Register Digital Input Register
Digital Input Register 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.
WR ITE
HOST SOFTWARE INTERFACE
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