am79c974 Advanced Micro Devices, am79c974 Datasheet - Page 38

• Manufacturer Part Number: am79c974
• Description: Pcnettm-scsi Combination Ethernet And Scsi Controller For Pci Systems
• Manufacturer: Advanced Micro Devices

Disconnect Without Data Transfer
Figure 12 shows a target disconnect sequence during
which no data is transferred. STOP is asserted on clock
4 without TRDY being asserted at the same time. The
Am79C974 controller terminates the current transfer
with the deassertion of FRAME on clock 5 and one clock
38
AMD
DEVSEL
FRAME
TRDY
STOP
IRDY
C/BE
REQ
GNT
CLK
PAR
AD
1
DEVSEL is sampled by the Am79C974 controller.
ADDRi
0111
2
DATA
Figure 12. Disconnect Without Data Transfer
PAR
3
0000
PAR
4
P R E L I M I N A R Y
Am79C974
5
cycle later with the deassertion of IRDY. It finally re-
leases the bus on clock 6. The Am79C974 controller will
re-request the bus after 2 clock cycles to retry the last
transfer. The starting address of the new transfer will be
the same address as of the last untransferred data.
6
7
8
9
10
ADDRi
0111
11
18681A-16