SBS Technologies 466-1, Hardware Manual

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Model 466-1 Adapter
VMEbus Adapter Card Configuration 35
Set the range to match the size of your Dual Port RAM. If the dual-port
memory is less than 64K bytes, set the range to 64K bytes.
Make sure no other VMEbus RAM or remote RAM are at the addresses
assigned for Dual Port RAM; if two memories are addressed at the same
location, neither memory can work properly.
Set the DUAL PORT LO jumpers to the first four digits of the eight-digit hex
VMEbus address for the memory block to be mapped to Dual Port RAM.
Assume that the remaining four digits of the hexadecimal address are all
zeros.
Set the DUAL PORT HI jumpers to the first address after the end of the
memory to be mapped to the Dual Port RAM.
VMEbus address space equal to or greater than the DUAL PORT LO setting
and less than the DUAL PORT HI setting is mapped to Dual Port RAM.
If Dual Port RAM is not installed or to disable Dual Port RAM, set the DUAL
PORT HI jumpers to a value less than the DUAL PORT LO jumpers.
Remember that if the A24 jumper is installed, the jumpers for A24 to A31
are ignored for A24 address modifiers.
All dual-port memory cards are designed to ignore unused upper address
bits when a large window is used (these bits are still used to determine
that access is in the window). For example, for a 1M byte Dual Port
RAM card, only Address Lines A19-A0 are significant; Address Lines
A31-A20 are ignored.
For any size Dual Port RAM, the dual-port window must start at an
address that is an integer multiple, starting from address zero, of the
selected Dual Port RAM size. Thus, for a 128K byte Dual Port RAM, the
window must start on a 128K byte address in the address space; for a 1M
byte Dual Port RAM, the window must start on a 1M byte address, and so
on.