Functional Description
Operating Modes
20
Zeus Ultra DMA Solid State Drives
2.3
O
PERATING
M
ODES
The Zeus SSD is configured as a high-performance I/O device, supporting the following
operating modes:
•
Primary drive address at system ATA I/O address 1F0h - 1F7h and 3F6h - 3F7h. The
host must provide chip-enable #CS0 and #CS1. The SSD decodes addresses DA0
- DA2.
•
Secondary drive address at system ATA I/O address 170h - 177h and 376h - 377h.
The host must provide chip-enable #CS0 and #CS1. The SSD decodes addresses
DA0 - DA2.
2.3.1
I/O Primary and Secondary ATA (IDE) Modes
Primary and secondary drive addressing modes allow hosts to use the ATA-standard’s
reserved disk drive I/O addresses. This provides computer system designers with the
simplest way to accommodate ATA-protocol devices.
2.3.1.1 Addressing Modes
Zeus SSDs, on a command by command basis, can operate in either CHS or LBA
addressing modes. Identify Drive Information (see “Identify Drive Information” on
page 23) tells the host whether the drive supports LBA mode. The host selects LBA
mode via the Drive/Head register. Sector Number, Cylinder Low, Cylinder High, and
Drive/Head register bits HS3=0 contain the zero-based LBA. The drive's sectors are
linearly mapped with: LBA = 0 => Cylinder 0, head 0, sector 1. Regardless of the
translation mode, a sector LBA address does not change. LBA = (Cylinder * no of heads
+ Head) * (sectors/track) + (Sector - 1). Table 6 on page 21 lists the supported IDE
addressing modes.
