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== '''Glossary''' ==  
== A ==


'''This page is a work in progress'''
=== ACPI ===
The '''Advanced Configuration & Power Interface''' is an industry standard for letting the OS control power management.
* [[ACPI|ACPI and coreboot]]
* http://www.acpi.info/
* http://en.wikipedia.org/wiki/Advanced_Configuration_and_Power_Interface
* http://kernelslacker.livejournal.com/88243.html (acpitool to generate a C source (see mailing list also))


'''MMIO''' (Memory-mapped I/O) and port I/O (also called port-mapped I/O or
=== AGP ===
PMIO) are two complementary methods of performing input/output
'''Advanced Graphics Port''', a point-to-point channel for attaching a video card to a mainboard with AGP slot.
between the CPU and I/O devices in a computer.
* http://en.wikipedia.org/wiki/Accelerated_Graphics_Port


http://encyclopedia.thefreedictionary.com/mmio
=== AGP Aperture ===
----------------------------------------------------
The memory range that is set aside for AGP access.
'''PIO''' (Programmed Input/Output) interface is the original method used to
* http://en.wikipedia.org/wiki/Accelerated_Graphics_Port
transfer data between the CPU (through the IDE controller) and an IDE/ATA
device.


http://encyclopedia.thefreedictionary.com/pio
=== AHCI ===
----------------------------------------------------
The '''Advanced Host Controller Interface'''. Describes the register-level interface for a SATA host controller.
The '''Framebuffer''' is a part of RAM in a computer allocated to hold the
* http://en.wikipedia.org/wiki/Advanced_Host_Controller_Interface
graphics information for one frame or picture. This information typically
* http://www.intel.com/technology/serialata/ahci.htm
consists of color values for every pixel on the screen.
* http://download.intel.com/technology/serialata/pdf/rev1_3.pdf (AHCI spec 1.3)
 
=== APIC ===
'''Advanced Programmable Interrupt Controller'''. An advanced version of a [[Glossary#PIC|PIC]] that can handle interrupts from and for multiple CPUs. Modern systems usually have several APICs: '''Local APICs''' (LAPIC) are CPU-bound, '''IO-APICs''' are bridge-bound.
* http://en.wikipedia.org/wiki/Advanced_Programmable_Interrupt_Controller
* http://osdev.berlios.de/pic.html
 
 
== B ==
 
=== BAR ===
'''Base Address Register''' (on PCI device).
* http://en.wikipedia.org/wiki/Base_Address_Register#Bus_enumeration
* http://wiki.osdev.org/PCI#Base_Address_Registers
 
=== BIOS ===
'''Basic Input/Output System'''.
* http://en.wikipedia.org/wiki/BIOS
 
=== BIST ===
The '''Built-In Self Test''', a selftest run by the processor when it is first started. Usually, any nonzero value indicates that the selftest failed.
 
== C ==
 
=== CAR ===
'''Cache as RAM'''.
 
=== CMOS ===
'''Complementary metal oxyde semiconductor''', a [http://en.wikipedia.org/wiki/CMOS class of semiconductors]. In the coreboot context CMOS (which is a bit of a misnomer here) usually refers to a chunk of non-volatile memory (NVRAM) in the PC, though.
* http://en.wikipedia.org/wiki/Nonvolatile_BIOS_memory
 
=== CPU ===
'''Central processing unit''' (e.g. an Athlon64).
* http://en.wikipedia.org/wiki/Central_processing_unit
 
=== crt0 ===
'''C Run Time 0''' - This is now called the romstage in coreboot.
* http://en.wikipedia.org/wiki/Crt0
 
=== crt0s ===
Sources that make up the romstage in coreboot, see [[#crt0|crt0]].
 
== D ==
 
=== DCR ===
'''Decode Control Register'''.
 
=== DID ===
'''Device ID''', a way of identifying the hardware in question. See [[Glossary#VID|VID]] for more info.
 
=== DMA ===
'''Direct Memory Access'''. Allows certain hardware subsystems within a computer to access system memory for reading and/or writing independently of the main CPU. Examples of systems that use DMA: Hard Disk Controller, Disk Drive Controller, Graphics Card, Sound Card.
DMA is an essential feature of all modern computers, as it allows devices of different speeds to communicate without subjecting the CPU to a massive interrupt load.
* http://en.wikipedia.org/wiki/Direct_memory_access
 
=== DSDT ===
'''Differentiated System Descriptor Table''', generated by BIOS and necessary for [[#ACPI|ACPI]]. Implementation of [[ACPI|ACPI in coreboot]] needs to be done in a "cleanroom" development process to avoid legal issues.
* http://acpi.sourceforge.net/dsdt/index.php
 
== E ==
 
=== EEPROM ===
Electrically erasable programmable ROM (common mistake: electrical erasable programmable ROM).
 
=== EHCI ===
Enhanced Host Controller Interface (USB host controller).
 
== F ==
 
=== Flashing ===
Flashing means writing of flash memory. The BIOS on modern mainboards is stored in a flash memory chip, which can be 128 Kilobytes to 4 Megabytes big.
 
=== Framebuffer ===
The '''Framebuffer''' is a part of RAM in a computer allocated to hold the graphics information for one frame or picture. This information typically consists of color values for every pixel on the screen.
A framebuffer is either:
A framebuffer is either:
* Off-screen, meaning that writes to the framebuffer don't appear on the visible screen
* Off-screen, meaning that writes to the framebuffer don't appear on the visible screen
* On-screen, meaning that the framebuffer is directly coupled to the visible display
* On-screen, meaning that the framebuffer is directly coupled to the visible display


http://encyclopedia.thefreedictionary.com/framebuffer
* http://en.wikipedia.org/wiki/Framebuffer
----------------------------------------------------
 
'''POST''' (Power On Self Test) is a test to check that devices the computer
 
will rely on are functioning, and initializes devices.
== G ==
 
=== GART ===
Graphics Address Relocation Table.
* http://www.linuxelectrons.com/article.php/20031021142247752
 
=== GATT ===
Graphics Aperture Translation Table.
* http://www.linuxelectrons.com/article.php/20031021142247752
 
=== GNB ===
Graphic NorthBridge.
 
Part of the newer AMD Fusion chips.
 
=== GPP ===
General Purpose Ports.
 
Part of the newer AMD Fusion chips.
 
=== GPIO ===
General Purpose Input/Output.
* http://en.wikipedia.org/wiki/GPIO
 
=== GSoC ===
[[GSoC|Google Summer of Code]].
 
== H ==
 
=== Hypertransport ===
A high-speed electrical interconnection protocol between CPU, memory and peripheral devices.
* http://en.wikipedia.org/wiki/Hypertransport
* http://www.hypertransport.org
* http://www.hotchips.org/archives/hc14/3_Tue/28_AMD_Hammer_MP_HC_v8.pdf
 
== I ==
 
=== I2C ===
'''Inter-Integrated-Circuit''', a bidirectional 2-wire bus for efficient inter-IC control.
* http://www.esacademy.com/faq/i2c/index.htm
 
=== IDSEL/AD ===
Initialization Device SELect/Address and Data. Each PCI slot has a signal called IDSEL. It is used to differentiate between the different cards?
* http://www.techfest.com/hardware/bus/pci.htm
* http://www.fpga4fun.com/PCI4.html
 
=== IRQ ===
Interrupt ReQuest (Handler).
 
 
== J ==
 
=== JTAG ===
Debugging and test 4-wire interface named after an organization which defined it.
 
== L ==
 
=== LAR ===
is the Linuxbios ARchiver, now called Lightweight [[LAR_Design|ARchiver]]. It is a small utility that we use to create and change coreboot images and their modules.
 
=== LPC ===
'''Low Pin Count''', an interface aimed at replacing the ISA bus.
* http://www.intel.com/design/chipsets/industry/lpc.htm
 
=== LRU ===
'''Least Recently Used''', a rule used in operating systems that utilises a paging system. LRU selects a page to be paged out if it has been used less recently than any other page. This may be applied to a cache system as well.
* http://computer.laborlawtalk.com/Least%20Recently%20Used
 
== M ==
 
=== Memory Training ===
 
'''Memory training''' is a very complex technlogical area. We are accumulating references to it as we find them.
 
* A [http://www.freshpatents.com/Training-of-signal-transfer-channels-between-memory-controller-and-memory-device-dt20080515ptan20080112255.php patent for GDDR4]
* Key to understanding training is the concept of an [http://en.wikipedia.org/wiki/Eye_diagram eye diagram]
 
It is amazing, but there is very little out there.
 
=== MII ===
'''Media Independent Interface'''. This is a chip commonly found on ethernet devices, together with a PHY.
* http://en.wikipedia.org/wiki/MII
 
=== MMIO ===
'''Memory-mapped I/O''' and port I/O (also called port-mapped I/O or PMIO) are two complementary methods of performing input/output between the CPU and I/O devices in a computer.
* http://en.wikipedia.org/wiki/MMIO
 
=== MPTable ===
'''Multi Processor Table'''. Intel MP specification is a hardware compatibility guide for machine hardware designers and OS software writers to produce SMP-capable machines and OSes in a vendor-independent manner. v1.1 and v1.4 versions exist.
* http://www.uruk.org/mps/
* http://www.intel.com/design/pentium/datashts/242016.htm
 
=== MTRR ===
'''Memory Type Range Register'''. This can be used to control the way a processor accesses memory ranges.
* http://en.wikipedia.org/wiki/MTRR
 
== O ==
 
=== OHCI ===
'''Open Host Controller Interface'''. IEEE1394 (Firewire) and USB standard (mostly used by other companies than Intel).
* http://en.wikipedia.org/wiki/Ohci
* http://developer.intel.com/technology/1394/download/ohci_11.htm
 
 
== P ==
 
=== PAM ===
'''Programmable Attribute Map'''. Hardware registers that describe how certain memory areas are accessed. The '''BIOS''' areas have a flash chip mapped on top of a piece of memory. By changing the '''PAM''' registers, accesses to these memory areas can be mapped to either the RAM or the flash device. '''Shadowing''' is implemented by setting read accesses to the flash device and write accesses to the same address space are mapped to RAM. Walking over the address space, each byte is read and immediately written from/to each address. Afterwards write accesses are ignored and read accesses are mapped to RAM. Usually the '''PAM''' registers are part of the southbridge of a system.
 
=== PAT ===
'''Page Attribute Table'''. Can be used independently or in combination with MTRR to setup memory type access ranges. Allows more finely-grained control than MTRR.
* http://www.intel.com/design/pentium4/manuals/index_new.htm
* http://66.102.9.104/search?q=cache:k5pI7x36u1kJ:www-gtr.iutv.univ-paris13.fr/Cours/Mat/Architecture/Docs/System.pdf+%22page+attribute+table%22&hl=en&start=10
 
=== PAT ===
Performance Acceleration Technology.
* http://www.intel.com/design/chipsets/pat.htm
 
=== PCI ===
Peripheral Component Interconnect.
* http://en.wikipedia.org/wiki/Peripheral_Component_Interconnect
 
=== PCI Configuration Space ===
* http://en.wikipedia.org/wiki/PCI_Configuration_Space
* http://www.techfest.com/hardware/bus/pci.htm
 
=== PCI Express / PCIe ===
* http://en.wikipedia.org/wiki/Pci_express
 
=== PHY ===
'''PHY layer device'''. A device that provides low level access to the physical layer.
* http://en.wikipedia.org/wiki/PHY
* http://foldoc.doc.ic.ac.uk/foldoc/foldoc.cgi?physical+layer
 
=== PIC ===
A '''Programmable Interrupt Controller''' is a device to control peripheral devices, offloading the main CPU.
* http://www.computer-dictionary-online.org/index.asp?q=programmable%20interrupt%20controller
* http://www.interq.or.jp/japan/se-inoue/e_pic1.htm
 
=== PIO ===
'''Programmed Input/Output''' interface is the original method used to transfer data between the CPU (through the IDE controller) and an IDE/ATA device.
* http://en.wikipedia.org/wiki/Programmed_input/output
 
=== PIR ===
Programmable Interrupt Routing?
 
=== PIRQ ===
PCI IRQ routing table,
* http://www.microsoft.com/whdc/archive/pciirq.mspx
* http://www.soundonsound.com/sos/jul04/articles/qa0704-1.htm
* Interesting tool?: https://bugzilla.redhat.com/bugzilla/attachment.cgi?id=93717&action=view
 
=== PLCC ===
'''Plastic Leaded Chip Carrier''', a square surface-mount chip package.
* http://en.wikipedia.org/wiki/Plastic_leaded_chip_carrier
* http://www.webopedia.com/TERM/P/PLCC.html
 
=== PLL ===
'''Phase Locked Loop''' is a device to keep (electrical) signals synchronised throughout the system.
* http://en.wikipedia.org/wiki/PLL
 
=== POST ===
The '''Power On Self Test''' is a test to check that devices the computer will rely on are functioning, and initializes devices.
* http://en.wikipedia.org/wiki/Power-on_self_test
 
== R ==
 
=== RDMA ===
'''Remote Direct Memory Access''' is a concept whereby two or more computers communicate via DMA directly from main memory of one system to the main memory of another.
* http://en.wikipedia.org/wiki/Remote_Direct_Memory_Access
 
=== RCS ===
Revision control systems.
 
== S ==
 
=== SB ===
'''Southbridge'''. Chip on the mainboard that is usually responsible for handling the flash device, IDE controller, ...


http://encyclopedia.thefreedictionary.com/booting
=== SBA ===
------------------------------------------
SideBand Addressing.
I2C - Inter-Integrated-Circuit, a bidirectional 2-wire bus for efficient
* http://www.linuxelectrons.com/article.php/20031021142247752
inter-IC control. See 'http://www.esacademy.com/faq/i2c/index.htm' for
more info.


Code examples(?): ...
=== Shadow RAM ===
------------------------------------------
RAM which content is copied from ROM residing at the same address for speedup purposes.
VID - Vendor ID, a way of identifying the hardware manufacturer. See
'http://www.microsoft.com/whdc/system/bus/PCI/infreq.mspx' and
'http://pciids.sourceforge.net/'
for more info.


A way of obtaining info for your hardware is through the 'lspci' command.
=== SIO ===
Simply type 'lspci -n' in the console (or an xterm) or 'lspci -vn' for
Serial Input/Output.
more verbose output.
* http://www.acronymfinder.com/af-query.asp?String=off&Acronym=sio&Find=Find&sourceid=mozilla-search
------------------------------------------
DID - Device ID, a way of identifying the hardware in question. See VID
(above) for more info.
----------------------------------------------------
DMA (Direct Memory Access) allows certain hardware subsystems within a
computer to access system memory for reading and/or writing independently
of the main CPU. Examples of systems that use DMA: Hard Disk Controller,
Disk Drive Controller, Graphics Card, Sound Card.
DMA is an essential feature of all modern computers, as it allows devices
of different speeds to communicate without subjecting the CPU to a massive
interrupt load.


http://encyclopedia.thefreedictionary.com/direct%20memory%20access
=== SMBus ===
----------------------------------------------------
The '''System Management Bus''' is a simple two-wire bus used for communication with low-bandwidth devices on a motherboard. It is based on (actually a subset of) I2C.
RDMA (Remote Direct Memory Access) is a concept whereby two or more
* http://www.smbus.org/
computers communicate via DMA directly from main memory of one system to
* http://www.computer-dictionary-online.org/index.asp?q=System%20Management%20Bus
the main memory of another.


http://encyclopedia.thefreedictionary.com/Remote%20Direct%20Memory%20Access
=== SMM ===
----------------------------------------------------
'''System Management Mode'''. Processor mode that is mainly used for power management purposes.
The purpose of the VGAcon (VGA controller) is to isolate the details of VGA
signal generation from all the other modules in a (hardware) design. It
allows the pixel information to be written into its video memory using a
very simple interface, while it is alone responsible for generating the
required signals for displaying the pixel information on a VGA monitor.
(Note: This is mostly relevant to a hardware design - the text is
copied from a students fpga project)


http://www.eecg.utoronto.ca/~singhd/241/vgacon.htm
=== SMRAM ===
----------------------------------------------------
System Management Random Access Memory.
AHCI (Advanced Host Controller Interface). Describes the register-level
interface for a SATA host controller.


http://encyclopedia.thefreedictionary.com/ahci
=== SOIC ===
http://www.intel.com/technology/serialata/ahci.htm
'''Small-Outline Integrated Circuit'''.
----------------------------------------------------
* http://en.wikipedia.org/wiki/Small-outline_integrated_circuit
OHCI (Open Host Controller Interface). IEEE1394 (Firewire) and
USB standard (mostly used by other companies than Intel)


http://encyclopedia.thefreedictionary.com/ohci
=== SPD ===
http://developer.intel.com/technology/1394/download/ohci_11.htm
'''Serial Presence Detect'''. On every (?) memory module there's an EPROM that provides the BIOS with information on how to properly configure the memory module.
----------------------------------------------------
* http://www.simmtester.com/page/news/showpubnews.asp?num=101
UHCI (Universal Host Controller Interface). USB standard.


http://encyclopedia.thefreedictionary.com/dict.asp?Word=uhci
=== SPI ===
http://developer.intel.com/technology/usb/uhci11d.htm
The '''Serial Peripheral Interface Bus''' is a very loose standard for controlling almost any digital electronics that accepts a clocked serial stream of bits.
----------------------------------------------------
* http://en.wikipedia.org/wiki/Serial_Peripheral_Interface_Bus
SPI (Serial Peripheral Interface Bus) is a very loose standard for
controlling almost any digital electronics that accepts a clocked serial
stream of bits.


http://encyclopedia.thefreedictionary.com/Serial%20Peripheral%20Interface
=== SuperIO ===
http://en.wikipedia.org/wiki/Serial_Peripheral_Interface_Bus
The '''SuperIO''' is the chip that provides floppy, serial and parallel functionality/ports.
----------------------------------------------------
* http://www.simtec.co.uk/products/EB7500ATX/files/EB7500ATX-mmap.html
SIO (Serial Input/Output)


http://www.acronymfinder.com/af-query.asp?String=off&Acronym=sio&Find=Find&sourceid=mozilla-search----------------------------------------------------
=== SSI-EEB ===
PIC (Programmable Interrupt Controller) is a device to control peripheral devices,
Physical board format - a wider version of ATX with different standoff placement
offloading the main CPU.
https://en.wikipedia.org/wiki/SSI_EEB


http://www.computer-dictionary-online.org/index.asp?q=programmable%20interrupt%20controller
If your desired case has enough space for an SSI-EEB motherboard on the board tray you can always drill and tap (thread) your own holes for the standoffs if you do not wish to buy another enclosure.
(Relevant???? -- http://www.superdroidrobots.com/pics.htm)
(remove the tray first and wipe it off to make sure there is no metal dust or fragments before you put it back)
(Relevant???? -- http://www.interq.or.jp/japan/se-inoue/e_pic1.htm)
----------------------------------------------------
PLL (Phase Locked Loop) is a device to keep (electrical) signals synchronised
throughout the system.


http://en.wikipedia.org/wiki/PLL
== T ==
----------------------------------------------------
SuperIO is (usually?) the chip that provides floppy, serial and parallel
functionality/ports.


http://www.simtec.co.uk/products/EB7500ATX/files/EB7500ATX-mmap.html
=== TLB ===
----------------------------------------------------
'''Translation Lookaside Buffer'''. The TLB stores the most recently used page-directory and page-table entries, which translates into speedier access to said memory.
SPD (Serial Presence Detect). On every (?) memory module there's
* http://www.linuxelectrons.com/article.php/20031021142247752
an eprom that provides BIOS with information on how to properly
* For more details see IA-32 Intel256 Architecture Software Developer's Manual: Vol3 Section 10.1
configure the memory module.


http://www.simmtester.com/page/news/showpubnews.asp?num=101
----------------------------------------------------
SMBus (System Management Bus) is a simple two-wire bus used for
communication with low-bandwidth devices on a motherboard. It is
based on (actually a subset of) I2C.


http://www.smbus.org/
== U ==
http://www.computer-dictionary-online.org/index.asp?q=System%20Management%20Bus
See I2C for more info.
----------------------------------------------------
ACPI (Advanced Configuration & Power Interface) is an industry standard
for letting the OS control power management.


http://www.acpi.info/
=== UC ===
http://www.computer-dictionary-online.org/index.asp?q=Advanced%20Configuration%20and%20Power%20Interface
Strong '''UnCacheable'''. Memory type setting in MTRR/PAT.
----------------------------------------------------
APIC (Advanced Programmable Interrupt Controller). An advanced version of
a PIC that can handle interrupts from and for multiple CPUs.


http://www.computer-dictionary-online.org/index.asp?q=Advanced%20Programmable%20Interrupt%20Controller
=== UC ===
http://osdev.berlios.de/pic.html
'''UnCacheable'''. Memory type setting in MTRR/PAT.
----------------------------------------------------
* For more details see IA-32 Intel256 Architecture Software Developer's Manual: Vol3 Section 10.3
VMEBus (VERSAmodule Eurocard Bus OR Versa Module Europa Bus). A computer bus
originally developed for the Motorola 68000.


http://encyclopedia.thefreedictionary.com/VMEbus
=== UHCI ===
----------------------------------------------------
'''Universal Host Controller Interface'''. USB standard.
PCI (Peripheral Component Interconnect).
* http://en.wikipedia.org/wiki/UHCI
* http://developer.intel.com/technology/usb/uhci11d.htm


http://encyclopedia.thefreedictionary.com/PCI
=== UMI ===
----------------------------------------------------
Unified Media Interface
PCI Configuration Space.


http://encyclopedia.thefreedictionary.com/PCI%20Configuration%20Space
== V ==
----------------------------------------------------
PIRQ (Pci IRQ routing table).


http://www.microsoft.com/whdc/archive/pciirq.mspx
=== VGAcon ===
http://www.rojakpot.com/default.aspx?location=8&var1=0&var2=148
The purpose of the '''VGAcon''' (VGA controller) is to isolate the details of VGA signal generation from all the other modules in a (hardware) design. It allows the pixel information to be written into its video memory using a very simple interface, while it is alone responsible for generating the required signals for displaying the pixel information on a VGA monitor. (Note: This is mostly relevant to a hardware design - the text is copied from a students FPGA project).
http://www.soundonsound.com/sos/jul04/articles/qa0704-1.htm
* http://www.eecg.utoronto.ca/~singhd/241/vgacon.htm
Interesting tool?:
https://bugzilla.redhat.com/bugzilla/attachment.cgi?id=93717&action=view
----------------------------------------------------
PAM (Programmable Attribute Map).


???
=== VID ===
----------------------------------------------------
'''Vendor ID''', a way of identifying the hardware manufacturer.
SMM (System Management Mode) or
* http://www.microsoft.com/whdc/system/bus/PCI/infreq.mspx
    (Shared Memory Module)   or
* http://pciids.sourceforge.net/
    (Shared Memory Multiprocessor)
A way of obtaining info for your hardware is through the 'lspci' command. Simply type 'lspci -n' in the console (or an xterm) or 'lspci -vn' for more verbose output.
???
----------------------------------------------------
SMRAM (System Management Random Access Memory).


???
=== VMEBus ===
----------------------------------------------------
'''VERSAmodule Eurocard Bus''' or '''Versa Module Europa Bus'''. A computer bus originally developed for the Motorola 68000.
MPTable (Multi Processor Table). Intel MP specification is a hardware
* http://en.wikipedia.org/wiki/VMEbus
compatibility guide for machine hardware designers and OS software
writers to produce SMP-capable machines and OSes in a vendor-independent manner.
v1.1 and v1.4 versions exist.


http://www.uruk.org/~erich/mps.html
== W ==
http://www.intel.com/design/pentium/datashts/242016.htm


=== WB ===
Write-Back. Memory type setting in MTRR/PAT.


----------------------------------------------------
=== WC ===
PIR
Write-Combining. Memory type setting in MTRR/PAT.


???
=== WP ===
----------------------------------------------------
Write Protected. Memory type setting in MTRR/PAT.
DCR (Decode Control Register)


???
=== WT ===
----------------------------------------------------
Write-Through. Memory type setting in MTRR/PAT.
* For more details see IA-32 Intel256 Architecture Software Developer's Manual: Vol3 Section 10.3

Latest revision as of 18:57, 28 January 2017

A

ACPI

The Advanced Configuration & Power Interface is an industry standard for letting the OS control power management.

AGP

Advanced Graphics Port, a point-to-point channel for attaching a video card to a mainboard with AGP slot.

AGP Aperture

The memory range that is set aside for AGP access.

AHCI

The Advanced Host Controller Interface. Describes the register-level interface for a SATA host controller.

APIC

Advanced Programmable Interrupt Controller. An advanced version of a PIC that can handle interrupts from and for multiple CPUs. Modern systems usually have several APICs: Local APICs (LAPIC) are CPU-bound, IO-APICs are bridge-bound.


B

BAR

Base Address Register (on PCI device).

BIOS

Basic Input/Output System.

BIST

The Built-In Self Test, a selftest run by the processor when it is first started. Usually, any nonzero value indicates that the selftest failed.

C

CAR

Cache as RAM.

CMOS

Complementary metal oxyde semiconductor, a class of semiconductors. In the coreboot context CMOS (which is a bit of a misnomer here) usually refers to a chunk of non-volatile memory (NVRAM) in the PC, though.

CPU

Central processing unit (e.g. an Athlon64).

crt0

C Run Time 0 - This is now called the romstage in coreboot.

crt0s

Sources that make up the romstage in coreboot, see crt0.

D

DCR

Decode Control Register.

DID

Device ID, a way of identifying the hardware in question. See VID for more info.

DMA

Direct Memory Access. Allows certain hardware subsystems within a computer to access system memory for reading and/or writing independently of the main CPU. Examples of systems that use DMA: Hard Disk Controller, Disk Drive Controller, Graphics Card, Sound Card. DMA is an essential feature of all modern computers, as it allows devices of different speeds to communicate without subjecting the CPU to a massive interrupt load.

DSDT

Differentiated System Descriptor Table, generated by BIOS and necessary for ACPI. Implementation of ACPI in coreboot needs to be done in a "cleanroom" development process to avoid legal issues.

E

EEPROM

Electrically erasable programmable ROM (common mistake: electrical erasable programmable ROM).

EHCI

Enhanced Host Controller Interface (USB host controller).

F

Flashing

Flashing means writing of flash memory. The BIOS on modern mainboards is stored in a flash memory chip, which can be 128 Kilobytes to 4 Megabytes big.

Framebuffer

The Framebuffer is a part of RAM in a computer allocated to hold the graphics information for one frame or picture. This information typically consists of color values for every pixel on the screen. A framebuffer is either:

  • Off-screen, meaning that writes to the framebuffer don't appear on the visible screen
  • On-screen, meaning that the framebuffer is directly coupled to the visible display


G

GART

Graphics Address Relocation Table.

GATT

Graphics Aperture Translation Table.

GNB

Graphic NorthBridge.

Part of the newer AMD Fusion chips.

GPP

General Purpose Ports.

Part of the newer AMD Fusion chips.

GPIO

General Purpose Input/Output.

GSoC

Google Summer of Code.

H

Hypertransport

A high-speed electrical interconnection protocol between CPU, memory and peripheral devices.

I

I2C

Inter-Integrated-Circuit, a bidirectional 2-wire bus for efficient inter-IC control.

IDSEL/AD

Initialization Device SELect/Address and Data. Each PCI slot has a signal called IDSEL. It is used to differentiate between the different cards?

IRQ

Interrupt ReQuest (Handler).


J

JTAG

Debugging and test 4-wire interface named after an organization which defined it.

L

LAR

is the Linuxbios ARchiver, now called Lightweight ARchiver. It is a small utility that we use to create and change coreboot images and their modules.

LPC

Low Pin Count, an interface aimed at replacing the ISA bus.

LRU

Least Recently Used, a rule used in operating systems that utilises a paging system. LRU selects a page to be paged out if it has been used less recently than any other page. This may be applied to a cache system as well.

M

Memory Training

Memory training is a very complex technlogical area. We are accumulating references to it as we find them.

It is amazing, but there is very little out there.

MII

Media Independent Interface. This is a chip commonly found on ethernet devices, together with a PHY.

MMIO

Memory-mapped I/O and port I/O (also called port-mapped I/O or PMIO) are two complementary methods of performing input/output between the CPU and I/O devices in a computer.

MPTable

Multi Processor Table. Intel MP specification is a hardware compatibility guide for machine hardware designers and OS software writers to produce SMP-capable machines and OSes in a vendor-independent manner. v1.1 and v1.4 versions exist.

MTRR

Memory Type Range Register. This can be used to control the way a processor accesses memory ranges.

O

OHCI

Open Host Controller Interface. IEEE1394 (Firewire) and USB standard (mostly used by other companies than Intel).


P

PAM

Programmable Attribute Map. Hardware registers that describe how certain memory areas are accessed. The BIOS areas have a flash chip mapped on top of a piece of memory. By changing the PAM registers, accesses to these memory areas can be mapped to either the RAM or the flash device. Shadowing is implemented by setting read accesses to the flash device and write accesses to the same address space are mapped to RAM. Walking over the address space, each byte is read and immediately written from/to each address. Afterwards write accesses are ignored and read accesses are mapped to RAM. Usually the PAM registers are part of the southbridge of a system.

PAT

Page Attribute Table. Can be used independently or in combination with MTRR to setup memory type access ranges. Allows more finely-grained control than MTRR.

PAT

Performance Acceleration Technology.

PCI

Peripheral Component Interconnect.

PCI Configuration Space

PCI Express / PCIe

PHY

PHY layer device. A device that provides low level access to the physical layer.

PIC

A Programmable Interrupt Controller is a device to control peripheral devices, offloading the main CPU.

PIO

Programmed Input/Output interface is the original method used to transfer data between the CPU (through the IDE controller) and an IDE/ATA device.

PIR

Programmable Interrupt Routing?

PIRQ

PCI IRQ routing table,

PLCC

Plastic Leaded Chip Carrier, a square surface-mount chip package.

PLL

Phase Locked Loop is a device to keep (electrical) signals synchronised throughout the system.

POST

The Power On Self Test is a test to check that devices the computer will rely on are functioning, and initializes devices.

R

RDMA

Remote Direct Memory Access is a concept whereby two or more computers communicate via DMA directly from main memory of one system to the main memory of another.

RCS

Revision control systems.

S

SB

Southbridge. Chip on the mainboard that is usually responsible for handling the flash device, IDE controller, ...

SBA

SideBand Addressing.

Shadow RAM

RAM which content is copied from ROM residing at the same address for speedup purposes.

SIO

Serial Input/Output.

SMBus

The System Management Bus is a simple two-wire bus used for communication with low-bandwidth devices on a motherboard. It is based on (actually a subset of) I2C.

SMM

System Management Mode. Processor mode that is mainly used for power management purposes.

SMRAM

System Management Random Access Memory.

SOIC

Small-Outline Integrated Circuit.

SPD

Serial Presence Detect. On every (?) memory module there's an EPROM that provides the BIOS with information on how to properly configure the memory module.

SPI

The Serial Peripheral Interface Bus is a very loose standard for controlling almost any digital electronics that accepts a clocked serial stream of bits.

SuperIO

The SuperIO is the chip that provides floppy, serial and parallel functionality/ports.

SSI-EEB

Physical board format - a wider version of ATX with different standoff placement https://en.wikipedia.org/wiki/SSI_EEB

If your desired case has enough space for an SSI-EEB motherboard on the board tray you can always drill and tap (thread) your own holes for the standoffs if you do not wish to buy another enclosure. (remove the tray first and wipe it off to make sure there is no metal dust or fragments before you put it back)

T

TLB

Translation Lookaside Buffer. The TLB stores the most recently used page-directory and page-table entries, which translates into speedier access to said memory.


U

UC

Strong UnCacheable. Memory type setting in MTRR/PAT.

UC

UnCacheable. Memory type setting in MTRR/PAT.

  • For more details see IA-32 Intel256 Architecture Software Developer's Manual: Vol3 Section 10.3

UHCI

Universal Host Controller Interface. USB standard.

UMI

Unified Media Interface

V

VGAcon

The purpose of the VGAcon (VGA controller) is to isolate the details of VGA signal generation from all the other modules in a (hardware) design. It allows the pixel information to be written into its video memory using a very simple interface, while it is alone responsible for generating the required signals for displaying the pixel information on a VGA monitor. (Note: This is mostly relevant to a hardware design - the text is copied from a students FPGA project).

VID

Vendor ID, a way of identifying the hardware manufacturer.

A way of obtaining info for your hardware is through the 'lspci' command. Simply type 'lspci -n' in the console (or an xterm) or 'lspci -vn' for more verbose output.

VMEBus

VERSAmodule Eurocard Bus or Versa Module Europa Bus. A computer bus originally developed for the Motorola 68000.

W

WB

Write-Back. Memory type setting in MTRR/PAT.

WC

Write-Combining. Memory type setting in MTRR/PAT.

WP

Write Protected. Memory type setting in MTRR/PAT.

WT

Write-Through. Memory type setting in MTRR/PAT.

  • For more details see IA-32 Intel256 Architecture Software Developer's Manual: Vol3 Section 10.3
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