Frequently Asked Questions
A-4
Mode Clock per
33MHz
PCI
Clock
count
Cycle
time
Data Transfer rate
PIO mode 0 30ns 20 600ns (1/600ns) x 2byte = 3.3MB/s
PIO mode 1 30ns 13 383ns (1/383ns) x 2byte = 5.2MB/s
PIO mode 2 30ns 8 240ns (1/240ns) x 2byte = 8.3MB/s
PIO mode 3 30ns 6 180ns (1/180ns) x 2byte = 11.1MB/s
PIO mode 4 30ns 4 120ns (1/120ns) x 2byte = 16.6MB/s
DMA mode 0 30ns 16 480ns (1/480ns) x 2byte = 4.16MB/s
DMA mode 1 30ns 5 150ns (1/150ns) x 2byte = 13.3MB/s
DMA mode 2 30ns 4 120ns (1/120ns) x 2byte = 16.6MB/s
DMA/33
30ns 4 120ns (1/120ns) x 2byte x2 = 33MB/s
Q: What is ACPI (Advanced Configuration & Power Interface) and OnNow?
A: The ACPI is new power management specification of 1997 (PC97). It intends
to save more power by taking full control of power management to operating
system and not through BIOS. Because of this, the chipset or super I/O chip
needs to provide standard register interface to OS (such as Win97) and
provides the ability for OS to shutdown and resume power of different part of
chip. The idea is a bit similar to the PnP register interface.
ACPI defines momentary soft power switch to control the power state
transition. Most likely, it uses the ATX form factor with momentary soft power
switch. The most attractive part of ACPI for desktop user is probably the
"OnNow" feature, an idea from notebook. This feature allows you to
immediately resume to your original work without the long time waiting from
bootup, entering Win95 and running Winword. Intel 430TX PCIset, 440LX
AGPset and 440BX AGPset can support ACPI.
Q: What is ATX Soft Power On/Off and Momentary Switch?
A: The Soft Power On of the ATX specification means to provide a standby
current for special circuit to wait for wakeup event when main power is off. For
example, Infrared wakeup, modem wakeup, or voice wakeup. Currently, the
most simple usage is to provide standby current for power switch circuit so
that power switch can turn on/off the main power through soft power control
pin. The ATX power specification does not mention anything about the power
switch type. You can use toggle or momentary switch, note that ACPI
specification requires momentary switch for power state control. All the
AOpen ATX MBs support momentary switch and AX5T/AX5TC/AX6L/AX6LC/
AX6B/AX6BC support modem wakeup (Modem Ring-On).
To Next Page
Loading...
Need help?
General
