SBS Technologies 466-1, Hardware Manual

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Model 466-1 Adapter
CSR Accessed From The SBus 57
The VMEbus Page Registers are gated to the VME address bus when the Use
Address Page Register command bit is set. The two Page Registers
together provide the upper 12 - 16 address bits of a 32-bit memory address.
The Address Page LOW Register provides the upper four to eight address bits
of a 24-bit memory address when accessing memory in 24-bit mode.
In the case of Dual Port RAM, the Dual Port RAM card ignores any address
bits larger than the size of the memory. For example, for a 1M byte Dual Port
RAM card, only A16 - A19 are significant. Setting the Page Register with a
value of F0xxxx or 00xxxx results in the exact same section of dual-port
memory being accessed.
6.2.5 Address Modifier Register
VMEbus addresses consist of 16, 24, or 32 address bits and a 6-bit address
modifier.
The Address Modifier Register is a byte access only, read/write register
located on the VMEbus adapter card. It is programmed by writing the desired
code to the Node I/O address 020 000C
hex .
The Address Modifier Register allows address modifier codes other than the
default codes (0D, 3D and 2D) to be generated from the SBus adapter card.
The code in the Address Modifier Register is passed to the VMEbus as the
address modifier only if jumper 1 in the VMEbus
SYS jumper block is
installed; see section 4.4. If jumper 1 is not installed, the default address
modifier codes are used.
BIT FUNCTION
7 Not Defined - must be "0"
6 Not Defined - must be "0"
5 VMEbus Address Modifier Bit 5
4 VMEbus Address Modifier Bit 4
3 VMEbus Address Modifier Bit 3
2 VMEbus Address Modifier Bit 2
1 VMEbus Address Modifier Bit 1
0 VMEbus Address Modifier Bit 0