
IBM3206K0424
Preliminary
IBM Processor for Network Resources
pnr25.chapt04.01
August 14, 2000
The IOP Bus Specific Interface Controller (PCINT)
Page 103 of 676
1.7: PCINT Base Addresses 3-6 (Memory)
This register specifies the base address of where in PCI memory space the IBM3206K0424 memory will be 
mapped. When written with 
’
1
’
s and read back, the least significant bits read back as 
’
0
’
 will indicate the 
amount of memory space required for this device to operate. For example, when a value of 
’
FFFFFFFF
’
 is 
written, a value read of 
’
FFFFFF00
’
 indicates that 256 bytes of address space this required. See bit defini-
tions. 
The mapping for the base address of registers into IBM3206K0424 memory is one-to-one, assuming a mem-
ory windowing option is not set in the PCINT Base Addr Control Register for that base address register 
(BAR). Multiple BARs are only used to use a given system memory map more efficiently. As required by the 
BAR, the addresses are size-aligned. For example, that means a 16MB size could be represented with one 
BAR as one 16MB size aligned on a 16MB boundary. However, four-4MB BARs could represent the same 
16MB size but be aligned on any 4MB boundary. The value in any of the BARs does not map directly to any 
particular IBM3206K0424 memory structure, such as Control Memory. The addresses are mapped using the 
Virtual, Packet, and Control base address registers in VIMEN.
When in 64-bit Addressing Mode (that is, bit 64 of PCINT 64-bit Control Register is set to 
’
1
’
):
Length
32 bits
Type
Read/Write
Address
Reg 3
XXXX 0018
Reg 4
XXXX 001C
Reg 5
XXXX 0020
Reg 6
XXXX 0024
Power on Reset value 
(Big Endian)
X
’
00000008
’
Power on Reset value 
(Little Endian)
X
’
08000000
’
Restrictions
Can be written or read during configuration cycle, memory cycle when enabled (see 
PCINT Base Address Control Register on page 111
), or an I/O cycle. This register 
is documented as big endian, but how data is presented on the PCI bus depends 
on how the controls are set in the PCINT Endian Control Register.
If one of these registers is not enabled (see PCINT Base Address Control Regis-
ter), then a read of that register will return all 
’
0
’
s. The power on value stated below 
assumes that the register is enabled. Normally, configuration code will just read 
these registers to find out what is there. To enable more that the default of registers 
3 and 4, the use of Crisco code could be used. See Entity 15: on page 428 for 
details. 
Base Address
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10
9
8
7
6
5
4
3
2
1
0
Bit(s)
PCI Spec
Name
Description
31-0
31-0
Upper part of Base Address
This register is used to hold the upper 32 bits of address during a 64 bit 
addressing dual cycle access.