DP83905AVQB National Semiconductor, DP83905AVQB Datasheet - Page 28

• Manufacturer Part Number: DP83905AVQB
• Description: IC CONTROLR AT/LAN TP IN 160PQFP
• Manufacturer: National Semiconductor
• Series: AT/LANTIC™r

Specifications of DP83905AVQB

• Controller Type: AT, LAN Twisted-Pair Interface Controller
• Voltage - Supply: 4.75 V ~ 5.25 V
• Current - Supply: 100mA
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 160-BFQFP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Interface: -
• Other names: *DP83905AVQB

Bits
D0-D5
D0–D4
D0
Bits
5 0 Register Descriptions
5 2 SHARED MEMORY MODE CONTROL REGISTERS
The following tables describe the functionality of the two control registers and the 8 16 detection registers
Shared Memory AT Detect Register (Read only)
Shared Memory Control Register 1
Shared Memory Control Register 2
Bits
D6
D7
D5
D6
D7
Symbols
ATDET
A13–A18
MEME
RESET
Symbols
LA19–LA23
MEMW
8 16
Symbols
ATDET This bit shows the value on the DWID pin and can be read by software to determine whether the
AT LANTIC Controller is operating in an 8- or 16-bit slot When this bit is read as a 1 the AT LANTIC Controller
is in a 16-bit slot (PC-AT system bus) and when read as a 0 it is in an 8-bit slot
A13–18 Lower part of the address register used to determine the position of the AT LANTIC
Controller’s memory within the system memory map
MEMORY ENABLE Enables external memory accesses when held high This bit will power up low
so the user must program the base memory address and set this bit high to enable the memory into
the system’s memory map
RESET Resets NIC core of AT LANTIC Controller
RESET
8 16
7
x
7
7
LA19–23 Upper part of the address register used to determine the position of the AT LANTIC
Controller’s memory within the system memory map
UNUSED
MEMORY WIDTH Sets width of external memory When set low external memory is accessed as
byte wide so only 8 kbytes of memory are available When set high external memory is accessed
as word wide so 16 kbytes are available In non-compatible mode up to 64 kbytes of external
memory is allowed when this bit is set high or 32 kbytes when low When bit 7 is set high this bit
must also be set high
8 16-BIT Allows 16-bit system accesses to external memory when set high When low only 8-bit
accesses are allowed When high the generation of the M16 output is allowed
MEMW
MEME
6
6
6
x
(Continued)
Unused
A18
5
5
x
5
LA23
A17
4
x
4
4
28
LA22
A16
3
3
x
Function
3
Function
Function
LA21
A15
2
x
2
2
LA20
A14
1
x
1
1
ATDET
LA19
A13
0
0
0