Seagate 810 manual ATA interface signals and connector pins, AT bus signal levels

Marathon 810 (ST9816AG) Product Manual, August 1995 21

3.0 ATA interface

The ST9816AG uses the industry-standard ATA interface. It supports both 8-bit and 16-bit data transfers. It supports ATA programmed in- put/output (PIO) modes 0, 1, 2, 3 and 4, ATA single-word DMA modes 0, 1 and 2, and ATA multiword DMA modes 0, 1 and 2. The drive also supports the use of the IORDY signal to provide reliable high-speed data transfers.

The drive can differentiate between a hard reset and a soft reset while in Sleep mode. You can use a daisy-chain cable to connect two drives to a single AT host bus. For detailed information regarding the ATA interface, refer to the Proposed Working Draft of the ATA-2 Draft Pro- posed American National Standard, document X3T9.2/948D (sub- sequently referred to as the Draft Proposed ATA-2 Standard).

3.1 ATA interface signals and connector pins

Figure 5 on page 22 summarizes the signals on the ATA interface connector that are supported by the ST9816AG. For a detailed descrip- tion of these signals, refer to the Draft Proposed ATA-2 Standard.

3.1.1AT bus signal levels

Signals that the drive sends have the following output characteristics at the drive connector:

Logic Low	0.0V to 0.4V
Logic High	2.5V to 5.25V

Signals that the drive receives must have the following input charac- teristics, measured at the drive connector:

Logic Low	0.0V to 0.8V
Logic High	2.0V to 5.25V