AM79C976 Advanced Micro Devices, AM79C976 Datasheet - Page 173

• Manufacturer Part Number: AM79C976
• Description: PCnet-PRO 10/100 Mbps PCI Ethernet Controller
• Manufacturer: Advanced Micro Devices

Control and Status Registers
The Control and Status Registers (CSRs) are included
for compatibility with older PCnet Family software. All
CSR functions can be accessed more efficiently through
the memory-mapped registers.
The CSR space is accessible by performing accesses
to the RDP (Register Data Port). The particular CSR
that is read or written during an RDP access will de-
pend upon the current setting of the RAP. RAP serves
as a pointer into the CSR space.
Am79C976 CSRs can be accessed at any time. For
older PCnet family devices certain CSRs could only be
accessed when the device is stopped.
Certain bits in CSR0 indicate the cause of an interrupt.
The register is designed so that these indicator bits are
cleared by writing ones to those bit locations. This
means that the software can read CSR0 and write back
the value just read to clear the interrupt condition.
Bit
31-16
15
14
13
12
11
10
8/01/00
Name
RES
ERR
BABL
CERR
MISS
MERR
RINT
zeros and read as undefined.
accessible. Read returns zero.
accessible. Read returns zero.
accessible. Read returns zero.
accessible. Read returns zero.
accessible. Read returns zero.
Am79C976 controller after the
last descriptor of a receive frame
has been updated by writing a 0
to the OWNership bit. RINT may
also be set when the first descrip-
tor of a receive frame has been
updated by writing a 0 to the
OWNership bit if the LAPPEN bit
of CSR3 has been set to a 1.
When RINT is set, INTA is assert-
ed if IENA is 1 and the mask bit
RINTM (CSR3, bit 10) is 0.
Reserved locations. Written as
Obsolete function. Read/Write
Obsolete function. Read/Write
Obsolete function. Read/Write
Obsolete function. Read/Write
Obsolete function. Read/Write
Receive Interrupt is set by the
Description
P R E L I M I N A R Y
Am79C976
9
8
7
TINT
IDON
INTR
Read/Write accessible. RINT is
cleared by the host by writing a 1.
Writing a 0 has no effect. RINT is
cleared
S_RESET, or by setting the
STOP bit.
When TINT is set, INTA is assert-
ed if IENA is 1 and the mask bit
TINTM (CSR3, bit 9) is 0.
Read/Write accessible. TINT is
cleared by the host by writing a 1.
Writing a 0 has no effect. TINT is
cleared
S_RESET, or by setting the
STOP bit.
When IDON is set, INTA is as-
serted if IENA is 1 and the mask
bit IDONM (CSR3, bit 8) is 0.
Read/Write accessible. IDON is
cleared by the host by writing a 1.
Writing a 0 has no effect. IDON is
cleared
S_RESET, or by setting the
STOP bit.
Am79C976 controller after the
OWN bit in the last descriptor of a
transmit frame has been cleared
to indicate the frame has been
copied to the transmit FIFO.
Am79C976 controller after the
initialization sequence has com-
pleted. When IDON is set, the
Am79C976 controller has read
the initialization block from mem-
ory.
Interrupt Flag indicates that one
or more following interrupt caus-
ing conditions has occurred:
IDON, RINT, SINT, TINT, TX-
STRT, UINT, STINT, MREINT,
MCCINT, MCCIINT, MIIPDTINT,
MAPINT, MPINT, APINT, LCINT,
SPNDINT and the associated
mask or enable bit is pro-
grammed to allow the event to
cause an interrupt. If IENA is set
to 1 and INTR is set, INTA will be
active. When INTR is set by SINT
or SLPINT, INTA will be active in-
dependent of the state of IENA.
Transmit Interrupt is set by the
Initialization Done is set by the
by
by
by
H_RESET,
H_RESET,
H_RESET,
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