GD82551QM INTEL [Intel Corporation], GD82551QM Datasheet - Page 49

• Manufacturer Part Number: GD82551QM
• Description: Fast Ethernet Multifunction PCI/CardBus Controller
• Manufacturer: INTEL [Intel Corporation]

7.0
7.1
7.2
7.3
Datasheet
Figure 13. Modem Read/Write Cycles
Modem Functionality
The local port mimics the standard 8-bit interface of a modem to the host system and emulates a
16550 Universal Asynchronous Receiver/Transceiver (UART) modem interface. The modem
interface includes the following:
PCI Address Mapping to the Modem
The modem can be accessed by the PCI bus through either I/O or memory mapping.
Modem Read and Write Cycles
Basic read/write cycles to the modem device are shown in the figure below.
Modem and Preboot eXtension Environment Coexistence
The 82551QM local bus can interface with a Flash device or modem without external support.
External logic can be implemented on the circuit board to support both devices by using the
Modem Chip Select (MDMCS#) and Flash Chip Select (FLCS#) signals.
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Modem Data In / Out
Modem WE# / RD#
Modem AEN (CS#)
8-bit data bus: FLD7:0
Control signals: AEN (FLCS#), MCNTSM# (FLA12), MINT (FLA11), MRING# (FLA10),
MRST (FLA9), RD# (FLOE#), and WR# (FLWE#)
4 address lines
Modem IOCHRDY
Modem Addrsess
t1
t2
t4
t9
t6'
Networking Silicon — 82551QM
t8
t10
t6
t3
t7
t5
t11
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