IBM IC35L020 - Deskstar 20 GB Hard Drive Specifications page 41

DD00–DD15 DD00–DD15 are the 16-bit bi-directional data bus signal names. These lines connect the
host and the drive. The lower 8 lines (DD00–07) are used for Register and ECC access.
All 16 lines (DD00–DD15) are used for data transfer. Each line is a 3-state lines with
24 mA current sink capability.
DA0-DA2 These addresses are used to select the individual register in the drive.
CS0- CS0- is the Chip Select signal generated from the Host address bus. When active, one of
the Command Block Registers [Data, Error (Features when written), Sector Count,
Sector Number, Cylinder Low, Cylinder High, Drive/Head and Status (Command when
written) register] can be selected. (See Figure 39 on page 43.)
CS1- CS1- is the chip select signal generated from the Host address bus. When active, one of
the Control Block Registers [Alternate Status (Device Control when written) and Drive
Address register] can be selected. (See Figure 39 on page 43.)
RESET- This signal is used to reset the drive. The drive requires that this line be kept at a logic
Low state during power up and in a High state thereafter.
DIOW- This signals rising edge holds data from the host data bus to a register or data register of
the HDD.
DIOR- When the DIOR- signal is low data is enabled from either a register or data register of the
drive onto the data bus. The data on the bus is latched on the rising edge of the DIOR-
signal.
INTRQ The interrupt request is enabled only when the drive is selected and the host activates
the nIEN bit in the Device Control Register. Otherwise, this signal is in a high impedance
state regardless of the state of the IRQ bit. The interrupt is set when the IRQ bit is set by
the drive CPU. The IRQ is reset to zero by a host read of the status register or a write to
the Command Register. This signal is a 3-state line with 24 mA sink capability.
IOCS16- This signal gives an indication to the host that a 16-bit wide data register has been
addressed and that the drive is prepared to send or receive a 16-bit wide data word. This
signal is an Open-drain output with 24 mA sink capability and an external resistor is
needed to pull this line up to 5 Volts.
DASP- This is a time-multiplexed signal which indicates that either a drive is active or that
Device 1 is present. This signal is driven by Open-Drain driver and internally pulled up to
5 Volts through a 10 K resistor.
During the Power-on initialization or after a RESET- is negated, DASP- is asserted by
Device 1 within 400 ms to indicate that Device 1 is present. Device 0 allows up to 450 ms
for Device 1 to assert the DASP- signal. If Device 1 is not present, Device 0 may assert
DASP- to drive an LED indicator.
DASP- is negated following acceptance of the first valid command by Device 1. Anytime
after negation of DASP- either drive (that is master or slave) may assert DASP- to
indicate that a drive is active.
PDIAG- The PDIAG- signal is asserted by Device 1 to indicate to Device 0 that it has completed
diagnostics. This line is pulled-up to +5 Volts in the drive through a 10 K resistor.
Following a Power On Reset, software reset, or RESET-, drive 1 negates PDIAG- within
1 ms (to indicate to Device 0 that it is busy). Drive 1 shall then assert PDIAG- within 30
seconds to indicate that it is no longer busy and is able to provide status.
Following the receipt of a valid Execute Drive Diagnostics command, Device 1 negates
PDIAG- within 1 ms to indicate to Device 0 that it is busy and has not yet passed its drive
diagnostics. If Device 1 is present then Device 0 waits up to 6 seconds from the receipt
Deskstar 60 GXP Hard disk drive specification
27