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22. Glossary

BDM

- Background Debug Mode

An on-chip debug interface supported by a special hardware port on some processors. It allows to take full control over the CPU with minimal external hardware, in many cases eliminationg the need for expensive tools like In-Circuit-Emulators.

BOOTP

- Boot Protokoll

A network protocol which can be used to inquire a server about information for the intended system configuration (like IP address, host name, netmask, name server, routing, name of a boot image, address of NFS server, etc.

CFI

- Common Flash Interface

CFI is a standard for flash chips that allows to create device independend drivers for such chips.

CPM

- Communications Processor Module

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

CramFs

- Compressed ROM File System

Cramfs is designed to be a simple, small, and compressed file system for ROM based embedded systems. CramFs is read-only, limited to 256MB file systems (with 16MB files), and doesn't support 16/32 bits uid/gid, hard links and timestamps.

CVS

- Concurrent Versions System

CVS is a version control system; it can be used to record the history of files, so that it is for instance possible to retrieve specific versions of a source tree.

DHCP

- Dynamic Host Configuration Protocol

A network protocol which can be used to inquire a server about information for the intended system configuration (like IP address, host name, netmask, name server, routing, name of a boot image, address of NFS server, etc.). Sucessor of BOOTP

DMA

- Direct Memory Access

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

ELDK

- Embedded Linux Development Kit

A package which contains everything you need to get startet with an Embedded Linux project on your hardware:

FEC

- Fast Ethernet Controller

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

FTP

- File Transfer Protocol

A protocol that can be used to transfer files over a network.

GPL

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

The full license text can be found at 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.

Host

The computer system which is used for software development. For instance it is used to run the tools of the ELDK to build software packages.

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.

JFFS

- Journalling Flash File System

JFFS (developed by Axis Communicartion AB, Sweden) is a log-based filesystem on top of the MTD layer; it promises to keep your filesystem and data in a consistent state even in cases of sudden power-down or system crashes. That's why it is especially useful for embedded devices where a regular shutdown procedure cannot always be guaranteed.

JFFS2

- Second version of the Journalling Flash File System

Like JFFS this is a journalling flash filesystem that is based on the MTD layer; it fixes some design problems of JFFS and adds transparent compression.

JTAG

- Joint Test Action Group

A standard (see "IEEE Standard 1149.1") that defines how to control the pins of JTAG compliant devices.

Here: An on-chip debug interface supported by a special hardware port on some processors. It allows to take full control over the CPU with minimal external hardware, in many cases eliminationg the need for expensive tools like In-Circuit-Emulators.

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.

MTD

- Memory Technology Devices

The MTD functions in Linux support memory devices like flash or Disk-On-Chip in a device-independend way so that the higher software layers (like filesystem code) need no knowledge about the actual hardware properties.

PC

Card?

PC Cards are self-contained extension cards especially for laptops and other types of portable computers. In just about the size of a credit card they provide functions like LAN cards (including wireless LAN), modems, ISDN cards, or hard disk drives - often "solid-state" disks based on flash chips.

The PC Card technology has been has been developed and standardized by the Personal Computer Memory Card International Association (PCMCIA), see http://www.pcmcia.org/pccard.htm .

PCMCIA

- Personal Computer Memory Card International Association

PCMCIA is an abbreviation that can stand for several things: the association which defines the standard, the specification itself, or the devices. The official term for the devices is PC-Card.

RTOS

- Real-Time Operating System

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.

SELF

- Simple Embedded Linux Framework

A simple default configuration for Embedded Linux systems that is suitable as starting point for building your own systems. It is based on BusyBox to provide an init process, shell, and many common tools (from cat and ls to vi), plus some other tools to provide network connectivity, allowing to access the system over the internet using telnet and FTP services.

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.

SPI

- Serial Peripheral Interface

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

S-Record

- Motorola S-Record Format

Motorola S-records are an industry-standard format for transmitting binary files to target systems and PROM programmers.

See also: http://pmon.groupbsd.org/Info/srec.htm

Target

The computer system which will be used later in you application environment, for instance an Embedded System. In many cases it has a different architecture and much more limited resoucres than a typical Host system, so it is often not possible to develop the software directly (native) on this system.

TFTP

- Trivial File Transfer Protocol

A simple network protocol for file transfer; used in combination with BOOTP or DHCP to load boot images etc. over the network.

21. Alternatives 1. Introduction 23. GNU Free Documentation License
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