A port replicator duplicates externally and extends features that are already available in a mobile PC—for example, an extra PC Card slot or keyboard and monitor connectors.
A port replicator with dedicated features allows the end user to add a specific feature to the original mobile PC—for example, a CD-ROM drive.
A mobile PC with a port replicator does not need to meet the expansion card requirements and does not need to meet all the resource requirements of a mobile PC/docking station combination. A port replicator is not required to provide an undock or eject button.
However, some mobile PC system designs include a port replicator that has dedicated features for networking, additional PC Card slots, a CD-ROM, and so on. This means that the system could have additional resource requirements to the point that all available IRQs in the system are already allocated; in this case, the PC Card slots (for example) would not have any IRQs available, rendering them useless.
In such cases, the port replicator must contain devices that replace any devices in the mobile PC that do not meet the IRQ, DMA, I/O port, and memory requirements for PC 98. This allows the operating system to disable the device on the mobile PC, to enable the corresponding device on the port replicator, and then to arbitrate resources among the remaining devices in the mobile unit and on the port replicator.
The requirements in this section apply for any port replicator designed for a PC 98 mobile PC. There is no requirement that a mobile PC must have a port replicator.
22. Port replicator supports automatic resource assignment and dynamic disable capabilities for replacement devices
Required
A port replicator that can accept expansion cards must contain devices that replace any devices in the mobile PC that do not meet Basic PC 98 requirements for IRQ, DMA, I/O port, and memory resources. This allows the operating system to disable the device on the mobile PC, to enable the corresponding device on the port replicator, and then to arbitrate resources among the remaining devices in the mobile unit and on the port replicator.
Devices in the system must be capable of being dynamically disabled so that the user can choose to free resources in order to allow other devices in the system to function.
Tip: To avoid resource shortages, the system designer can take advantage of the capability of Yenta-compliant CardBus controllers’ capability to assign a shared PCI interrupt for R2 PC Cards, rather than using IRQs, as defined in the “PC Card 16 card driver supports sharing of level-mode interrupts” item in the “PC Card” chapter in Part 3 of this guide. For more information, see the related article at http://www.microsoft.com/hwdev/busbios/.
23. Port replicator supports warm docking
Required
Docking or undocking a mobile unit from a port replicator must not require powering off the system and must not require a system reboot.
Removable IDE devices are not required to meet this requirement.