Phoebe 2100: PCI & Podules
Wakefield '98
Peripheral Component Interconnect (PCI) Bus
- The new expansion bus for Phoebe, a common standard on PCs, Apple Macs and UNIX workstations.
- Implements a 32 bit bus, running at a clock speed of 33MHz.
- Four PCI slots are provided, on a riser that attaches to the edge of the motherboard.
- The interface between the internal and PCI busses is handled by a PCI Bridge, the PLX Technology 9080.
- The PCI Bridge handles the protocol conversion for data travelling to and from the PCI bus
- It also arbitrates the Master/Slave relationship between devices on the bus. This allows other devices - a PC card, for example - to temporarily take control of the bus.
- It will be possible to use standard PCI cards on this bus. However, drivers will have to be written to allow Phoebe to access them.
- Care has been taken in designing the PCI bus to ensure that it is correctly terminated. This is essential of the bus is to run reliably at high speed.
- Dave Walker mentioned that a driver for a 3Dfx three-dimensional graphics accelerator is currently in development.
- Acorn also expect the PCI bus to be used to provide network support. Dave Walker pointed out that PCI interfaces are available for 10Base and 100Base Ethernet, 25Mbit/s to 155Mbit/s Asynchronous Transfer Mode (ATM), and even Fibre Distributed Data Interface (FDDI).
Podule Bus
- Phoebe has three Podule sockets, mounted on a riser card.
- The full Podule Bus has been implemented to ensure hardware compatibility with existing devices.
- A longer riser card, with more sockets, would be possible electrically. However, the case design limits further expansion this way.
- The Podule Bus runs at 8MHz, as before.
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