am79c970 Advanced Micro Devices, am79c970 Datasheet - Page 31

• Manufacturer Part Number: am79c970
• Description: Pcnettm-pci Single-chip Ethernet Controller For Pci Local Bus
• Manufacturer: Advanced Micro Devices

Preemption When FRAME is Asserted
The central arbiter can take GNT to the PCnet-PCI con-
troller away if the current bus operation takes too long.
This may happen e.g. when the PCnet-PCI controller
tries to fill the whole transmit FIFO and the target inserts
extra wait states for every data phase. When GNT is
taken away, the PCnet-PCI controller will finish the
1-898
AMD
DEVSEL
FRAME
TRDY
IRDY
C/BE
REQ
GNT
PAR
CLK
AD
1
DEVSEL is sampled by the PCnet-PCI controller.
Figure 11. Preemption When FRAME is Asserted
2
3
P R E L I M I N A R Y
ADDR
0111
4
Am79C970
DATA
PAR
5
0000
current transfer and then immediately release the bus.
The Latency Timer in PCI configuration space of the
PCnet-PCI controller is always set to ZERO. The PCnet-
PCI controller will keep REQ asserted to regain bus
ownership as soon as possible.
PAR
6
DATA
7
DATA
PAR
8
PAR
9
18220C-13