Programming Scatter-Gather Ram; Access To Pci Memory Addresses - DEC Digital Alpha VME 4/224 User Manual

The windows defined by these registers must not overlap each other. The
following sections describe these registers and the region of address space they
define.
Table 10–15 Access to PCI Memory Addresses
Register
VME_CSR_BASE
VME_WINDOW_1_BASE
VME_SG_BASE
VME_WINDOW_2_BASE

10.5.2 Programming Scatter-Gather RAM

To configure the VME interface for both master and slave operation, the scatter-
gather entries for both inbound and outbound accesses must be programmed to
provide address translation between the VMEbus and the PCI bus. The scatter-
gather RAM can be programmed independently of master or slave VMEbus
activity.
PCI
Configuration
Address
Space Purpose
00000810 This register gives access to the DC7407,
VIC64, and CY7C964 registers when the
base address of a window in PCI memory
space is written into the register. The
window is a 512-byte address region in
PCI memory space, aligned on a 512-byte
boundary.
<31:9> are writeable.
The locations of the VME interface
registers are identified as VME_CSR_
BASE + xxxx, representing their address in
PCI memory space.
00000814 This register gives access to VME address
space when the base address of a window
in PCI memory space is written into the
register. Only bits <31:29> are writable
because the 512 MB window must be
aligned on a natural boundary.
00000818 This register gives access to scatter-gather
RAM when the base address of a 128 KB
window in PCI memory space is written
into the register.
0000081C This register gives access to VME address
space when the base address of a second
window in PCI memory space is written
into the register. Only bits <31:26> are
writable because the 64 MB window must
be aligned on a natural boundary.
VME Interface 10–31