This section defines the general requirements for system buses. Additional requirements for specific buses are defined in Part 3 of this guide.
24. Each bus meets written specifications and PC 98 requirements
Consumer PC 98
Office PC 98
Entertainment PC 98
Required
Required
Required
In the past, some bus designs did not fully implement all of the bus requirements on every expansion card connector. For PC 98, each bus used in the system must meet all the requirements for that bus as defined in Part 3 of this guide.
Each bus and device provided in a PC 98 system must also meet the current Plug and Play specifications related to its class, including requirements defined in the ACPI 1.0 specification and the clarifications published for some Plug and Play specifications. This includes requirements for automatic device configuration, resource allocation, and dynamic disable capabilities. See also the related Plug and Play requirements in the “Basic PC 98 General Device Requirements” section earlier in this chapter.
25. System includes USB with one USB port, minimum
Consumer PC 98
Office PC 98
Entertainment PC 98
Required
Required
Required, with 2 USB ports
Recommended: 2 ports.
USB provides a bi-directional, isochronous, dynamically attachable serial interface for adding peripheral devices, such as game controllers, communications devices, and input devices, on a single bus.
The USB controller must be capable of waking the system as defined in Section 3.4.4 of the ACPI 1.0 specification. This capability is part of the requirement for ACPI compliance, as defined in the requirement, “System design meets ACPI 1.0 specification and PC 98 requirements,” earlier in this chapter.
The USB implementation in the system must also meet the requirements defined in the USB specifications plus any additional requirements for PC 98 defined in the “USB” chapter in Part 3 of this guide.
26. System includes support for other high-speed expansion capabilities
Consumer PC 98
Office PC 98
Entertainment PC 98
Recommended
Recommended
Required, with 2
IEEE 1394 ports
Recommended: Use either SCSI or IEEE 1394 as the default I/O port for devices such as scanners and external drives that require high-speed data transfer.
For all PC 98 systems, additional support for expansion capabilities can be provided using PCI 2.1, IEEE 1394, CardBus, or other high-speed buses. Any expansion bus implemented in the system must meet the requirements defined in the related chapter in Part 3 of this guide. For information about Device Bay requirements, see the “Device Bay-capable bay and peripherals meet Device Bay specification” requirement earlier in this chapter.
For Net PC systems, external expansion capabilities that are accessible by the end user are not recommended, with the exception of USB and Device Bay. If expansion capabilities are implemented in a Net PC system, additional requirements are defined in the Network PC System Design Guidelines.
27. If present, PCI bus meets PCI 2.1 or higher, plus PC 98 requirements
Consumer PC 98
Office PC 98
Entertainment PC 98
Required
Required
Required
If PCI is used in a PC system, the PCI bus must meet the requirements defined in PCI 2.1 or higher, plus any additional requirements for PC 98 defined in the “PCI” chapter in Part 3 of this guide. Exceptions for particular devices are noted in Parts 3 and 4 of this guide.
Add-on PCI IDE devices must comply with PCI 2.1 requirements and also must provide Subsystem IDs and Subsystem Vendor IDs. However, PCI-to-PCI bridges and core chip sets do not have to provide Subsystem IDs and Subsystem Vendor IDs.
All PCI connectors on the system board must be able to allow any PCI expansion card to have bus master privileges.
28. System does not include ISA expansion devices
Consumer PC 98
Office PC 98
Entertainment PC 98
Required
Required
Required, with no ISA slots
ISA expansion devices cannot be included in a PC 98 system, although ISA expansion slots are allowed on Consumer PC 98 and Office PC 98 systems. It is acceptable for all PC 98 systems to use ISA protocols and signaling or ISA-like protocols and signaling for an internal implementation. On-board devices such as audio, modems, or network adapters are not acceptable for PC 98, nor can the IDE controller use an ISA bus.
There will be a delayed phase-in period for this requirement, during which only system-board ISA devices will be allowed. Please notice that the ISA requirements that apply during the transition phase are the same as those defined in PC 97 Hardware Design Guide, and are also summarized in the “Legacy Support” appendix in the References part of this guide.
For Entertainment PC 98, the system must not contain ISA expansion slots that can be accessed by the end user. This is also a requirement for Net PC systems and is strongly recommended for workstations.
The benefits of designing ISA-free systems include easier and more stable system configuration, lower support cost, and improved performance.
For on-board legacy implementations, interrupts are supported using the legacy 8259 or (for Windows NT 5.0) APIC. Any on-board legacy implementations, such as BIOS ROM, Super I/O, 8042 controllers, math coprocessors, and so on, are allowed and must meet the requirements defined in the “Legacy Support” appendix in the References part of this guide.