
S5935 – PCI Product
16 DS1527
AMCC Confidential and Proprietary
Revision 1.02 – June 27, 2006
Data Book
Add-On Bus Operation Registers
The third and last register group consists of the Add-
On Operation Registers, shown in Table 3. This group
of eighteen 32-bit (DWORD) registers is accessible to
the Add-On Local bus. These are the main registers
through which the Add-On logic configures S5935
operation and communicates with the PCI Local bus.
These registers encompass the Add-On bus Mail-
boxes, Add-On FIFO, DMA Address/Count Registers
(when Add-On initiated Bus Mastering), Pass-Thru
Registers and Status/Control registers.
Non-Volatile Memory Interface
The S5935 contains a set of PCI Configuration Regis-
ters. These registers can be initialized with default
values or with designer specified values contained in
an external nvRAM. The nvRAM can be either a serial
(2 Kbytes, maximum) or a byte-wide device (64
Kbytes, maximum).
Table 2. PCI Operation Registers
PCI Operation Registers
Address
Offset
Outgoing Mailbox Register 1 (OMB1)
00h
Outgoing Mailbox Register 2 (OMB2)
04h
Outgoing Mailbox Register 3 (OMB3)
08h
Outgoing Mailbox Register 4 (OMB4)
0Ch
Incoming Mailbox Register 1 (IMB1)
10h
Incoming Mailbox Register 2 (IMB2)
14h
Incoming Mailbox Register 3 (IMB3)
18h
Incoming Mailbox Register 4 (IMB4)
1Ch
FIFO Register Port (bidirectional) (FIFO)
20h
Master Write Address Register (MWAR)
24h
Master Write Transfer Count Register (MWTC)
28h
Master Read Address Register (MRAR)
2Ch
Master Read Transfer Count Register (MRTC)
30h
Mailbox Empty/Full Status Register (MBEF)
34h
Interrupt Control/Status Register (INTCSR)
38h
Bus Master Control/Status Register (MCSR)
3Ch
Table 2. PCI Operation Registers
PCI Operation Registers
Address
Offset