System Buses

This section defines requirements for buses provided in a Net PC system.

43. Each bus complies with written specifications and PC 97 requirements

Required

Each bus used in the system must meet all the requirements for that bus as defined in Part 3 of PC 97 Hardware Design Guide. This includes the requirement to meet the current Plug and Play specifications related to its class, requirements defined in the ACPI specification, and clarifications published for some Plug and Play specifications. This also includes requirements for automatic device configuration, resource allocation, and dynamic disable capabilities.

44. Universal Serial Bus with one USB port, minimum

Required

The USB implementation in the system must meet the requirements defined in USB specifications, plus the additional requirements for PC 97 as defined in the “USB” chapter of PC 97 Hardware Design Guide.

45. PCI bus meets PCI 2.1 specifications and PC 97 requirements

Required

If PCI is used in a Net PC system, the PCI bus must meet the requirements defined in PCI version 2.1 or higher, plus the additional requirements for PC 97 as defined in the “PCI” chapter of PC 97 Hardware Design Guide.

Exceptions for particular devices are noted in Parts 3 and 4 of PC 97 Hardware Design Guide. For example, add-on PCI IDE devices must comply with PCI 2.1 requirements and also must provide Subsystem IDs and Subsystem Vendor IDs, but PCI-to-PCI bridges and core chip sets do not have to provide Subsystem IDs and Subsystem Vendor IDs.

July 1, 1997, is the compliance date for PCI motherboard devices and for PCI add-on adapters for PCI 2.1 Subsystem IDs. For more information, see the guidelines on http://www.microsoft.com/hwdev/busbios/idpnp.htm.

46. Support for high-speed expansion buses meets PC 97 and Net PC requirements, if present

Required

For Net PC systems, internal expansion capabilities that are accessible by the end user are not allowed. However, if implemented in a Net PC system, all high-speed expansion buses and expansion devices must meet the requirements as specified in Parts 3 and 4 of PC 97 Hardware Design Guide. This includes requirements for IEEE 1394 and CardBus, if implemented.

The following are specifically required for Net PC systems:

• Any bus that supports hot plugging or a device designed to use such a bus must support adding or removing devices while the system is fully powered.
• Any devices provided as expansion devices must be capable of being remotely disabled, including the capability to disable drives (CD-ROM, floppy drive, and so on), ensuring that control and TCO policies can be realized. For information about requirements for remote management capabilities, see the “Platform Management Information Requirements” section earlier in this document and the related attachments.

  47. Device Bay-capable bay and peripherals

  Recommended

  If implemented in a Net PC system, Device Bay capabilities must meet the following requirements

• A Device Bay controller, compliant with Device Bay Interface Specification, Version 1.0 and implemented as an ACPI device object on the system board.
• One USB controller and one IEEE 1394 controller to support all Device Bay-capable bays in the system.
• One USB port and one IEEE 1394 port for each Device Bay-capable bay in the system.

  Any Device Bay peripherals provided with a Net PC system must meet the following requirements.

• Peripherals compliant with Device Bay Interface Specification, Version 1.0.
• Peripherals interface with either the USB or IEEE 1394 bus, or both.
• Support relevant USB device class specifications.

  The following is specifically required for Net PC systems:

• Any devices provided as expansion devices must be capable of being remotely disabled, including the capability to disable drives (CD-ROM, floppy drive, and so on), ensuring that control and TCO policies can be realized. For information about requirements for remote management capabilities, see the “Platform Management Information Requirements” section earlier in this document and the related attachments.

  48. ISA bus expansion slots must not be provided

  Required

  No ISA bus expansion slots are permitted in a Net PC system. The benefits of an ISA-free Net PC system for administrative support personnel include easier and more stable configuration, lower support costs, and improved performance.

  This requirement does not preclude the inclusion of embedded ISA devices in a system board design. However, such devices, along with all other system board devices and system boards in general, must fully comply with all Net PC requirements for ACPI, OnNow, and system board device requirements. The end result must always be that all devices on a system board are fully and completely capable of software detection, configuration, and control.