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Adapter configurations 85
o
Normal Behavior: The value will be used to configure the 82557 at initialization time. Setting it
to a low value will force frequent internal arbitration, which will affect overall performance. The
value can be tuned to obtain optimum balance between the TX and Rx DMA machines.
o Possible Errors:
If the RXDMACOUNT parameter is set to an invalid value, the parameter is ignored and the
default value is used, and a message indicates a "Parameter value out of range" error.
• TXDMACOUNT
o Syntax: TXDMACOUNT=[0..127 | 0x0..0x7F]
o Example: TXDMACOUNT=16
o Default: 0 implying that the Tx DMA will continue until it is done. No other DMA request can
preempt it.
o Normal Behavior: The value will be used to configure the 82557 at initialization time. Setting it
to a low value will force frequent internal arbitration, which will affect overall performance. The
value can be tuned to obtain optimum balance between the Tx and Rx DMA machines.
o Possible Errors:
If the TXDMACOUNT parameter is set to an invalid value, the parameter is ignored and the
default value is used, and a message is indicates a "Parameter value out of range" error.
• TRANSMITBUFFERS
o Syntax: TRANSMITBUFFERS=[4 .. 30]
o Example: TRANSMITBUFFERS=14
o Default: 4 for DOS driver, 10 for OS/2 driver
o Normal Behavior: The driver allocates the number of buffers indicated by the parameter value.
o Possible Errors:
If the value provided is out of range, the parameter is ignored and the default value is used, and
a message indicates a "Parameter value out of range" error.
CAUTION: If the number of buffers allocated causes the driver’s size to exceed MAXIMUM,
the driver adjusts the number of buffers downward, by reducing each of the counts of
transmit/receive buffers by one until the total allocation will fit in the available memory. A
message indicates the actual number of buffers allocated. Under DOS without Window for
Workgroups (WFW), MAXIMUM is defined as 64Kb for all code and data.
Under DOS and WFW, the driver must not claim more space than its load size, but since the
driver cannot detect that it is running under WFW, a message warns the user when the size
allocated exceeds the size of the driver when loaded. Under OS/2, MAXIMUM is defined as
64Kb for all data.
• RECEIVEBUFFERS
o Syntax: RECEIVEBUFFERS=[4 .. 30]
o Example: RECEIVEBUFFERS=14
o Default: 8 for DOS driver, 10 for OS/2 driver
o Normal Behavior: The driver allocates the number of buffers indicated by the parameter value.
o Possible Errors:
If the value provided is out of range, the parameter is ignored, the default value is used, and a
message indicates a "Parameter value out of range" error.