
Applied Micro Circuits Corporation
6195 Lusk Blvd., San Diego, CA 92121 (619) 450-9333
5-4
PCI CONTROLLER
S5933
DEVICE SPECIFICATION
5.1
OUTGOING MAILBOX REGISTERS (OMB)
Register Names:
Outgoing Mailboxes 1-4
PCI Address Offset: 00h, 04h, 08h, 0Ch
Power-up value:
XXXXXXXXh
Attribute:
Read/Write
Size:
32 bits
These four DWORD registers provide a method for
sending command or parameter data to the Add-On
system. PCI bus operations to these registers may
be in any width (byte, word, or DWORD). Writing to
these registers can be a source for Add-On bus inter-
rupts (if desired) by enabling their interrupt genera-
tion through the use of the Add-On’s interrupt control/
status register (Section 6.9).
5.2
INCOMING MAILBOX REGISTERS (IMB)
Register Names:
Incoming Mailboxes 1-4
PCI Address Offset: 10h, 14h, 18h, 1Ch
Power-up value:
XXXXXXXXh
Attribute:
Read Only
Size:
32 bits
These four DWORD registers provide a method for
receiving user defined data from the Add-On system.
PCI bus read operations to these registers may be in
any width (byte, word, or DWORD). Only read opera-
tions are supported. Reading from these registers
can optionally cause an Add-On bus interrupt (if de-
sired) by enabling their interrupt generation through
the use of the Add-On’s interrupt control/status regis-
ter (described in Section 6.9).
Mailbox 4, byte 3 only exists as device pins on the
S5933 devices when used with a serial nonvolatile
memory.
This location provides access to the bidirectional
FIFO. Separate registers are used when reading
from or writing to the FIFO. Accordingly, it is not pos-
sible to read what was written to this location. The
FIFO registers are implicitly involved in all bus master
operations and, as such, should not be accessed
during active bus master transfers. When operating
upon the FIFOs with software program transfers in-
volving word or byte operations, the
endian sequence
of the FIFO should be established as outlined in Sec-
tion 11.1.1.2 in order to preserve the internal FIFO
data ordering and flag management. The FIFO’s full-
ness may be observed by reading the master control-
status register, MCSR, described in Section 5.10.
5.3
FIFO REGISTER PORT (FIFO)
Register Name:
FIFO Port
PCI Address Offset: 20h
Power-up value:
XXXXXXXXh
Attribute:
Read/Write
Size:
32 bits