ROBO-503/ROBO-503N
ROBO-503/ROBO-503N User’s Manual
31
3.7.16.7 Bus Arbitration
DRQ [0:3],
DRQ [5:7]
These signals are active high signals driven by a DMA bus adapter to indicate a request for a
DMA bus operation. DRQ [0:3] request 8 bit DMA operations, while DRQ [5:7] request 16 bit
operations. All bus DMA adapters will drive these lines with a tri-state driver. The permanent
master monitors these signals to determine which of the DMA devices, if any, are requesting
the bus.
DACK [0:3]#,
DACK [5:7]#
These signals are active low signals driven by the permanent master to indicate that a DMA
operation can begin. They are continuously driven by a totem pole driver for DMA channels
attached.
AEN
This signal is an active high totem pole signal driven by the permanent master to indicate that
the address lines are driven by the DMA controller. The assertion of AEN disables response to
I/O port addresses when I/O command strobes are asserted. AEN being asserted, only the
device with active DACK
n
# should respond.
REFRESH#
This is an active low signal driven by the current master to indicate a memory refresh operation.
The current master will drive this line with a tri-state driver.
TC
This active high signal is asserted during a read or write command indicating that the DMA
controller has reached a terminal count for the current transfer. DACK
n
# must be presented by
the bus adapter to validate the TC signal.
MASTER#
This signal is not supported by the chipset.
3.7.17 Fan Connector (CN7)
Signal
PIN
VCC
1
GND
2
