Vme Interface; System Resources; Vmebus Master Interface - Xycom XVME-655 Manual

VME Interface

The VME interface consists of the Universe chip, which is a PCI bus-to-VMEbus
interface. The XVME-655 is a 32-bit PCI interface and a 32-/64-bit VMEbus interface.
The Universe chip configuration registers are located in a 64 Kbyte block of PCI
memory space. This memory location is programmable and defined by PCI configuration
cycles. The Universe configuration register space should be set up using PCI interrupt
calls provided by the BIOS.
For information on accessing the PCI bus, refer to the PCI BIOS Functions section later
in this chapter.
The Universe manual states that the Universe Control and Status
Registers (UCSR) occupy 4 Kbytes of internal memory. While this is
true, the Universe controller decodes the entire 64 Kbyte region and
shadows the 4 Kbytes 16 times.

System Resources

The XVME-655 automatically detects slot 1 system resource functions. The system
resource functions are explained in the Universe manual.

VMEbus Master Interface

The XVME-655 can be a VMEbus master by accessing a PCI slave channel or by the
DMA channel initiating a transaction. The Universe chip contains four PCI slave images.
The first slave image has a 4 Kbyte resolution; the others have a 64 Kbyte resolution.
The VMEbus master can generate A16, A24, A32 VMEbus cycles for each PCI slave
image.
The address mode and type are programmed on a PCI slave image basis. The PCI
memory address location for the VMEbus master cycle is specified by the Base and
Bound address. The VME address is calculated by adding the Base address to the
Translation Offset address. All PCI slave images are located in the PCI bus memory
space.
All VMEbus master cycles are byte-swapped to maintain address coherency.
If you want to use the XVME-655 as a VMEbus master and slave, the
VMEbus master cycles must acquire the VMEbus prior to accessing the
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Caution
Note
PCI memory slave access = VMEbus master access
PCI memory master access = VMEbus slave access
Caution
Chapter 4 – Programming
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