LAN91C96I_07 SMSC [SMSC Corporation], LAN91C96I_07 Datasheet - Page 40

• Manufacturer Part Number: LAN91C96I_07
• Description: Non-PCI Single-Chip Full Duplex Ethernet Controller
• Manufacturer: SMSC [SMSC Corporation]

Rev. 03-28-07
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For software compatibility with other LAN9000 parts all memory-related information is represented in 256 x
M byte units, where the multiplier M is determined by the MCR upper byte. M equals “1” for the
LAN91C96I.
FREE MEMORY AVAILABLE - This register can be read at any time to determine the amount of free
memory. The register defaults to the MEMORY SIZE upon reset or upon the RESET MMU command.
MEMORY SIZE - This register can be read to determine the total memory size, and will always read 18H
(6144 bytes) for the LAN91C96I.
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MEMORY RESERVED FOR TRANSMIT - Programming this value allows the host CPU to reserve
memory to be used later for transmit, limiting the amount of memory that receive packets can use up.
When programmed for zero, the memory allocation between transmit and receive is completely dynamic.
When programmed for a non-zero value, the allocation is dynamic if the free memory exceeds the
programmed value, while receive allocation requests are denied if the free memory is less or equal to the
programmed value. This register defaults to zero upon reset. It is not affected by the RESET MMU
command.
The value written to the MCR is a reserved memory space IN ADDITION TO ANY MEMORY
CURRENTLY IN USE. If the memory allocated for transmit plus the reserved space for transmit is required
to be constant (rather than grow with transmit allocations) the CPU should update the value of this register
after allocating or releasing memory.
OFFSET
OFFSET
0
0
0
0
A
8
LAN91C100
LAN91C92/
LAN91C96I
LAN91C90
LAN91C90
LAN91C94
LAN91C95
MEMORY CONFIGURATION
0
0
0
0
MEMORY INFORMATION REGISTER
Memory Reserved for Transmit (in BYTES * 256 * M)
FREE MEMORY AVAILABLE (in BYTES* 256* M)
REGISTER
NAME
0
0
1
0
MEMORY SIZE (in BYTES* 256* M)
MEMORY SIZE REGISTER
DATASHEET
NAME
1
1
1
0
FFH
FFH
40H
12H
18H
18H
Page 40
lower byte READ/WRITE
upper byte READ ONLY
Memory Size Multiplier “M”
0
0
1
1
Non-PCI Single-Chip Full Duplex Ethernet Controller
M
TYPE
1
1
1
1
1
2
READ ONLY
0
0
0
0
TYPE
ACTUAL MEMORY
4608 bytes
6144 bytes
6144 bytes
128 kbytes
64 kbytes
16 kbytes
1
0
0
0
SYMBOL
SYMBOL
MCR
SMSC DS – LAN91C96I
MIR
1
0
0
0