22. Glossary

ABI Application Binary Interface

The convention for register usage and C linkage commonly used on desktop PowerPC machines. Similar, but not identical to the EABI.

BDM - Background Debug Mode

An on-chip debugging interface, largely eliminating the need for expensive In-Circuit Emulators.

CPM - Communications Processor Module

The magic communications co-processor in Motorola PowerQUICC devices. It contains SCCs and SMCs, and performs SDMA and IDMA.

CPU - Central Processor Unit

Depending on the context, this may refer to the PowerPC core itself, or the physical processor device (including CPM, SIU, packaging etc) as a single unit.

DMA - Direct Memory Access

A form a data transfer directly between memory and a peripheral or between memory and memory, without normal program intervention.

EABI - Embedded Application Binary Interface

The convention for register usage and C linkage commonly used on embedded PowerPC machines, derived from the ABI.

FEC - Fast Ethernet Controller

The 100 Mbps (100Base) Ethernet controller, present on 'T' devices such as the 860T and 855T.

GPL/LGPL - GNU General Public License/Lesser General Public License

http://www.gnu.org/copyleft/gpl.html

The licenses under which the Linux kernel and much of the utility and library code necessary to build a complete system may be copied, distributed and modified. Each portion of the software is copyright by its respected copyright holder, and you must comply with the terms of the license in order to legally copy (and hence use) it. One significant requirement is that you freely redistribute any modifications you make; if you can't cope with this, embedded Linux isn't for you.

IDMA - Independent DMA

A general purpose DMA engine with relatively limited throughput provided by the microcoded CPM, for use with external peripherals or memory-to-memory transfers.

MII - Media Independent Interface

The IEEE Ethernet standard control interface used to communicate between the on-chip Ethernet controller and the external PHY.

MMU - Memory Management Unit

CPU component which maps kernel- and user-space virtual addresses to physical addresses, and is an integral part of Linux kernel operation.

PHY - Physical Interface

The IEEE Ethernet standard interface between the external physical layer transceiver and the on-chip ethernet controller in a PowerQUICC device. Often used to refer to the external transceiver itself, the PHY is controlled more or less transparently to software via the MII.

SCC - Serial Communications Controller

The high performance module(s) within the CPM which implement the lowest layer of various serial protocols, such as Asynchronous serial (UART), 10 Mbps Ethernet, HDLC etc.

SDMA - Serial DMA

DMA used to transfer data to and from the SCCs.

SIU - System Interface Unit

Provides much of the external interfacing logic. It's the other major module on Motorola PowerQUICC devices alongside the CPU core and CPM.

SPI - Serial Peripheral Interface

A relatively simple synchronous serial interface for connecting low speed external devices using minimal wires.

SMC - Serial Management Controller

A lower performance version of the SCCs with more limited functionality, particularly useful for serial debug ports and low throughput serial protocols.

UART - Universal Asynchronous Receiver Transmitter

Generically, this refers to any device capable of implementing a variety of asynchronous serial protocols, such as RS-232, HDLC and SDLC. In this context, it refers to the operating mode of the SCCs which provides this functionality.

UPM - User Programmable Machine

A highly flexible bus interfacing machine unit allowing external peripherals with an extremely wide variety of interfacing requirements to be connected directly to the CPU.