Other Bus Requirements

This section summarizes requirements related to other buses.

Any subsystems implementing I₂O comply with standards and other requirements

Required

If I₂O is implemented in a system, it must meet the requirements defined in this guide and in the I₂O Architecture Specification, Version 1.5 or later, available from the I₂O Special Interest Group (SIG) at http://www.i2osig.org.

If I₂O is implemented on a system, the system BIOS must support I₂O devices in the system in the following cases:

• An I₂O-capable system that includes no I₂O-intelligent devices, whether provided on the system board set or as add-on devices. The system can have an installed adapter that is I₂O-ready or I₂O-compliant, and the BIOS must initialize the device as a multifunction device. The system cannot boot from this I₂O device, because the BIOS does not support initialization of I₂O bootable device.
  
  
• An I₂O-ready system that has some sort of intelligence on the system board set or on an add-on adapter that enables sending and receiving messages, as defined in the I₂O specification. This intelligence can be an off-the-shelf processor, an application-specific integrated circuit (ASIC) when it is on the system board set, or it can be included as an add-on adapter. In these cases, the system BIOS must support initializing and configuring the device, including support for multifunction PCI. Initialization and configuration of a PCI device does not imply that the system BIOS supports compliant I₂O initialization of boot devices or that the system can boot from an I₂O device.
  
  
• An I₂O-compliant system that includes support for initializing and booting from I₂O devices, whether provided on the system board set or as add-on devices. The system as a whole must be able to pass I₂O compliance testing with Windows NT 5.0.

System does not include ISA expansion slots

Required

No ISA expansion slots are allowed in servers designed to comply with these guidelines. The benefits of an ISA-free system include improved performance, easier and more stable system configuration, and lower support costs.

Out-of-band systems management devices that can be implemented in an ISA slot are the only case where an ISA slot can be present in a server. These exemptions provide a transition period for these specific technologies as they migrate to deterministic bus designs. It is anticipated that these exemptions will not be present in future versions of these guidelines.

System does not include embedded ISA network adapters, storage controllers, or graphics adapters

Required

The benefits of an ISA-free system include improved performance, easier and more stable system configuration, and lower support costs.

System does not include ISA expansion devices

Required

An ISA expansion device in this context is defined as being an expansion adapter or device installed in an ISA slot.

No ISA expansion devices are allowed, with specific exemptions for out-of-band systems management devices that can be implemented in an ISA slot; this is the only case where an ISA slot can be present in a server. These exemptions provide a transition period for these specific technologies as they migrate to deterministic bus designs. It is anticipated that these exemptions will not be present in future versions of these guidelines.

System includes APIC support

Required

This requirement does not apply for DEC Alpha servers.

The server must include APIC support that complies with ACPI 1.0, implemented by including the Multiple APIC Description Table (ACPI Section 5.2.8). Features such as targeted interrupts, broadcast interrupts, and prior-owner interrupts must be supported. Intel Architecture processor implementations can use the Intel APIC component.

Implementation of APIC support on server systems provides a greater number of IRQ resources, even within traditional server architectures.