Control Diagnostic Registers; Alternate Status Register; Device Control Register; Digital Input Register - Maxtor 2B020H1 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
3F6h Alternate Status
3F7h D igital Input

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:
7 6
0 0
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:
7 6
x -W G
Reserved Write
Gate
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
F ixed Di sk C ontrol
Not us ed
5 4
0 0
5 4
-HS3 -HS2 -HS1
Head Head Head
Select 3 Select 2 Select 1
3 2 1
0 SRST IEN
Reset IRQ Enable
3 2 1
-HS0 -DS1
Head D ri ve
Select 0 Select 1
HOST SOFTWARE INTERFACE
0
0
0
DS0
D ri ve
Select 0
6 – 5