Filter
Top Products
Product Description
23
1.7 Parallel IDE Controller
The Parallel ATA IDE controller has one bus-mastering Parallel ATA IDE interface. The
Parallel ATA IDE interface supports the following modes:
• Programmed I/O (PIO): processor controls data transfer.
• 8237-style DMA: DMA offloads the processor, supporting transfer rates of up to
16 MB/sec.
• Ultra DMA: DMA protocol on IDE bus supporting host and target throttling and
transfer rates of up to 33 MB/sec.
• ATA-66: DMA protocol on IDE bus supporting host and target throttling and
transfer rates of up to 66 MB/sec. ATA-66 protocol is similar to Ultra DMA and is
device driver compatible.
• ATA-100: DMA protocol on IDE bus allows host and target throttling. The ATA-100
logic can achieve read transfer rates up to 100 MB/sec and write transfer rates up
to 88 MB/sec.
NOTE
ATA-66 and ATA-100 are faster timings and require a specialized cable to reduce
reflections, noise, and inductive coupling.
The Parallel ATA IDE interface also supports ATAPI devices (such as CD-ROM drives)
and ATA devices. The BIOS supports Logical Block Addressing (LBA) and Extended
Cylinder Head Sector (ECHS) translation modes. The drive reports the transfer rate
and translation mode to the BIOS.
For information about Refer to
The location of the Parallel ATA IDE connector Figure 10, page 44
1.8 Real-Time Clock Subsystem
A coin-cell battery (CR2032) powers the real-time clock and CMOS memory. When
the computer is not plugged into a wall socket, the battery has an estimated life of
three years. When the computer is plugged in, the standby current from the power
supply extends the life of the battery. The clock is accurate to ± 13 minutes/year at
25 ºC with 3.3 VSB applied.
NOTE
If the battery and AC power fail, custom defaults, if previously saved, will be loaded
into CMOS RAM at power-on.
When the voltage drops below a certain level, the BIOS Setup program settings stored
in CMOS RAM (for example, the date and time) might not be accurate. Replace the
battery with an equivalent one.
Figure 1 on page 12 shows the location of the battery.