Memory Space Base Register (Pcimbr) - Hitachi SH7751 Hardware Manual

22.2.33 Memory Space Base Register (PCIMBR)

Bit: 31
MBR31
Initial value: 0
PCI-R/W: —
PP Bus-R/W: R/W
Bit: 23
—
Initial value: 0
PCI-R/W: —
PP Bus-R/W: R
Bit: 15
—
Initial value: 0
PCI-R/W: —
PP Bus-R/W: R
Bit: 7
—
Initial value: 0
PCI-R/W: —
PP Bus-R/W: R
The memory space base register (PCIMBR) specifies the most significant 8 bits of the address of
the PCI memory space when performing a memory read/write operation using PIO transfers. It
also specifies locked transfers. This 32-bit read/write register can be accessed from the PP bus.
All bits of the PCIMBR register are initialized to 0 at a power-on reset. They are not initialized at
a software reset.
Setting bit 0 (LOCK) to 1 locks the memory space for PIO transfers while the bit remains set. A
locked transfer consists of the combined read and write operations. Do not attempt to perform
other PIO transfers during the locked combination of read and write operations.
Always write to this register prior to performing memory read/write operations by PIO transfer.
30 29
MBR30 MBR29 MBR28
0 0
— —
R/W R/W
22 21
— —
0 0
— —
R R
14 13
— —
0 0
— —
R R
6 5
— —
0 0
— —
R R
28 27
MBR27 MBR26
0 0
— —
R/W R/W
20 19
— —
0 0
— —
R R
12 11
— —
0 0
— —
R R
4 3
— —
0 0
— —
R R
Rev. 3.0, 04/02, page 867 of 1064
26 25
MBR25 MBR24
0 0
— —
R/W R/W R/W
18 17
— —
0 0
— —
R R
10 9
— —
0 0
— —
R R
2 1
— — LOCK
0 0
— —
R R R/W
24
0
—
16
—
0
—
R
8
—
0
—
R
0
0
—