
=
- COMBE[2]/
XROMCS#
(inout) :
PCI cycles
AIO cycles
- COMBE[1]/
XWR#
(inout) :
PCI cycles
AIO cycles
- COMBE[0]/
XRD#
(inout) :
PCI cycles
AIO cycles
- INTD#/
XGLBCS#
(output) :
PCI cycles
AIO cycles
The above information is the exclusive intellectual property of Winbond Electronics and shall not be disclosed, distributed or reproduced without permission from Winbond.
32
Versi on 0. 4, March/2000
Application Notes :
AIO bus is designed to connect ISA-like, low speed devices such as code-ROM, Flashs and 8-/16-bit IO
devices. The AIO controller itself is a PCI slave device, if the address and access type of any PCI cycle
match the AIOBASE or XMBASE[8:15] of AIO, the AIO controller responds the DEVSEL# and TRDY# to
PCI bridge and generate correspond AIO bus signals to AIO devices in the "data phase" of current PCI
cycle.
XMBASE[7] will be set right from chip reset, all PCI cycles will be treated as AIO access and all code
read (PCI cycles) will return data from AIO bus. After the memory (XMBASE) and IO (AIOBASE) have been
properly configured, XMBASE[7] shall be set logic low immediately to avoid possible wrong response from
AIO controller.
Because XROMCS#, AIOCS#, XRD# and XWR# are shared the same pins with COMBE[0:3] of PCI bus,
they might toggle during any PCI cycles. It is necessary to OR these control signals with INTD
#, which dedicately serve as "AIO global chip-select", before they reaching the AIO devices.
The following figures show some typical timing diagrams of AIO command cycles :
: Bit-2 of command/byte bus
: AIO chip-select for its memory devices
: Bit-1 of command/byte bus
: Asserted low, if INTD# is also low, indicating a AIO write command cycle is ongoing.
: Bit-0 of command/byte bus
: Asserted low, if INTD# is also low, indicating a AIO read command cycle is ongoing.
: If AIO is enable, this signal shall not connect to any PCI bus master.
: Asserted low indicating a AIO command cycle is ongoing.
FRAME#
PDA[31:24]
PDA[7:0]
PCICLK
Fig 5.8.1 Fastest XIO IO read cycle (0 wait)
PDA[23:8]
16-bit IO address
DEVSEL#
INTD#
COMBE_3#
COMBE_2#
COMBE_1#
COMBE_0#
TRDY#
Low byte data
High byte data