Configuring Device Addresses

Configuring Device Addresses

Normally a VME card can be programmed to use different VME addresses for PIO, based on jumper or switch settings on the card. The devices on a single VME bus must be configured to use unique addresses. Errors that are hard to diagnose can arise when multiple cards respond to the same bus address. Devices on different VME buses can use the same addresses.

Not all parts of each address space are accessible. The accessible parts are summarized in Table 13-5.

Accessible VME Addresses in Each System
Address Space Crimson Series Challenge and Onyx Systems
A16 All All
A24 0x80 0000-0xFF FFFF 0x80 0000-0xFF FFFF
A32 0x1000 0000-0x1FFF FFFF (one bus)
0x1800 0000-0x1FFF FFFF (2 buses)
0x0000 0000-0x7FFF FFFF (maximum of 96 MB in 8 MB units)

Accessible VME Addresses in Each System
Address Space	Crimson Series	Challenge and Onyx Systems
A16	All	All
A24	0x80 0000-0xFF FFFF	0x80 0000-0xFF FFFF
A32	0x1000 0000-0x1FFF FFFF (one bus) 0x1800 0000-0x1FFF FFFF (2 buses)	0x0000 0000-0x7FFF FFFF (maximum of 96 MB in 8 MB units)

Within the accessible ranges, certain VME bus addresses are used by Silicon Graphics VME devices. You can find these addresses documented in the /var/sysgen/system/irix.sm file. You must configure OEM devices to avoid the addresses used by Silicon Graphics devices that are installed on the same system.

Finally, on the Challenge and Onyx systems, take care to cluster PIO addresses in the A32 space so that they occupy at most a 96 MB span of addresses. The reasons are explained under "Fixed PIO Maps".