AM79C978 Advanced Micro Devices, AM79C978 Datasheet - Page 39

• Manufacturer Part Number: AM79C978
• Description: Single-Chip 1/10 Mbps PCI Home Networking Controller
• Manufacturer: Advanced Micro Devices

Expansion ROM Transfers
Since the Am79C978 device does not have expansion
ROM capabilities, PCI configuration offset must be set
to 30H = 0.
During the boot procedure, the system will try to find an
Expansion ROM. A PCI system assumes that an Ex-
DEVSEL
FRAME
TRDY
STOP
C/BE
IRDY
PAR
CLK
AD
DEVSEL
FRAME
TRDY
STOP
IRDY
C/BE
PAR
CLK
AD
1
Figure 6. Slave Write Using Memory Command
ADDR
0111
DEVSEL is sampled
1
2
ADDR
CMD
PAR
2
Figure 7. Expansion ROM Read
3
PAR
3
BE
4
4
Am79C978
5
5
DATA
pansion ROM is present when it reads the ROM signa-
ture 55H (byte 0) and AAH (byte 1).
Slave Cycle Termination
There are three scenarios besides normal completion
of a transaction where the Am79C978 controller is the
target of a slave cycle and it will terminate the access.
6
BE
PAR
7
48
8
49
DATA
9
50
PAR
10
51
11
22206B-10
22206B-9
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