Editing Amiga (section)

== Hardware ==
[[File:Amiga 1000 computer.jpg|thumb|[[Amiga 1000]] front and back]]
[[File:Amiga 600.jpg|thumb|[[Amiga 600]]]]
[[File:Amiga 1200 with mouse, drives.jpg|thumb|[[Amiga 1200]]]]
[[File:Amiga-CD32-wController-L.jpg|thumb|[[Amiga CD32|CD32]]]]

The Amiga has a custom chipset consisting of several [[coprocessor]]s which handle audio, video, and [[direct memory access]] independently of the [[central processing unit]] (CPU). This architecture gave the Amiga a performance edge over its competitors, particularly for graphics-intensive applications and games.<ref name="amiga_hardware_ref" />

The architecture uses two distinct [[bus (computing)|bus]] subsystems: the chipset bus and the CPU bus. The chipset bus allows the coprocessors and CPU to address [[Amiga Chip RAM|"Chip RAM"]]. The CPU bus provides addressing to conventional RAM, ROM and the [[Zorro II]] or [[Zorro III]] expansion subsystems. This enables independent operation of the subsystems. The CPU bus can be much faster than the chipset bus. CPU expansion boards may provide additional custom buses. Additionally, "busboards" or "bridgeboards" may provide [[Industry Standard Architecture|ISA]] or [[Conventional PCI|PCI]] buses.<ref name="amiga_hardware_ref" />

=== Central processing unit ===
The most popular models from Commodore, including the [[Amiga 1000]], [[Amiga 500]], and [[Amiga 2000]], use the [[Motorola 68000]] as the CPU. From a developer's point of view, the 68000 provides a full suite of [[32-bit]] operations, but the chip can address only 16&nbsp;MB of physical memory and is implemented using a 16-bit [[arithmetic logic unit]] and has a 16-bit external [[data bus]], so 32-bit computations are transparently handled as multiple 16-bit values at a performance cost.<ref name="AutoP5-4" /><ref name="AutoP5-5" /> The later [[Amiga 2500]] and the [[Amiga 3000]] models use fully 32-bit, 68000-compatible processors from Motorola with improved performance and larger addressing capability.

CPU upgrades were offered by both Commodore and third-party manufacturers. Most Amiga models can be upgraded either by direct CPU replacement or through expansion boards. Such boards often included faster and higher capacity memory interfaces and [[hard disk]] controllers.

Towards the end of Commodore's time in charge of Amiga development, there were suggestions that Commodore intended to move away from the 68000 series to higher performance [[RISC]] processors, such as the [[PA-RISC]].<ref name="actuator" /><ref name="Haynie" /> Those ideas were never developed before Commodore filed for bankruptcy. Despite this, third-party manufacturers designed upgrades featuring a combination of 68000 series and PowerPC processors along with a PowerPC native [[microkernel]] and software.<ref name="AutoP5-6" /><ref name="AutoP5-7" /> Later Amiga clones featured [[PowerPC]] processors only.

=== Custom chipset ===
The custom chipset at the core of the Amiga design appeared in three distinct generations, with a large degree of backward-compatibility. The [[Original Chip Set]] (OCS) appeared with the launch of the A1000 in 1985. OCS was eventually followed by the modestly improved [[Enhanced Chip Set]] (ECS) in 1990 and finally by the partly 32-bit [[Advanced Graphics Architecture]] (AGA) in 1992. Each chipset consists of several coprocessors that handle [[blitter|graphics acceleration]], digital audio, [[direct memory access]] and communication between various peripherals (e.g., CPU, memory and floppy disks). In addition, some models featured auxiliary [[Amiga custom chips|custom chip]]s that performed tasks such as [[SCSI]] control and display de-interlacing.

==== Graphics ====
[[File:HAM6example.png|thumb|4096 color [[Hold-And-Modify|HAM]] picture created with [[Photon Paint]] in 1989]]
[[File:Amiga 2000 Wikipedia logo.jpg|thumb|An image in PAL 640x512 16 color mode displayed by an [[Amiga 2000]] on a Commodore 1084 monitor]]

All Amiga systems can display full-screen animated [[Planar (computer graphics)|planar]] graphics with 2, 4, 8, 16, 32, 64 ([[Amiga Halfbrite mode|EHB Mode]]), or 4096 colors ([[Hold-And-Modify|HAM Mode]]). Models with the AGA chipset (A1200 and A4000) also have non-EHB 64, 128, 256, and 262144 ([[Hold-And-Modify|HAM8 Mode]]) color modes and a palette expanded from 4096 to [[24-bit color|16.8 million colors]].

The Amiga chipset can ''[[genlock]]'', which is the ability to adjust its own screen refresh timing to match an incoming NTSC or PAL video signal. When combined with setting transparency, this allows an Amiga to overlay an external video source with graphics. This ability made the Amiga popular for many applications, and provides the ability to do [[Character generator|character generation]] and [[Computer-generated imagery|CGI]] effects far more cheaply than earlier systems. This ability has been frequently utilized by wedding videographers, TV stations and their weather forecasting divisions (for weather graphics and radar), advertising channels, music video production, and desktop videographers. The [[NewTek]] [[Video Toaster]] was made possible by the genlock ability of the Amiga.

In 1988, the release of the Amiga A2024 fixed-frequency [[monochrome monitor]] with built-in [[framebuffer]] and [[flicker fixer]] hardware provided the Amiga with a choice of high-resolution graphic modes (1008×800 for NTSC and 1008×1024 for PAL) with 4 [[Grayscale]] levels.<ref name="AutoP5-8" /><ref>https://www.infania.net/misc/gona/Commodore/monitor/manuals/Commodore_A2024_High_Resolution_Monitor_Users_Guide.pdf</ref>

==== ReTargetable Graphics ====
{{Main|ReTargetable Graphics}}

ReTargetable Graphics is an [[API]] for [[device driver]]s mainly used by 3rd party graphics hardware to interface with AmigaOS via a set of [[library (computing)|libraries]]. The software libraries may include software tools to adjust [[Display resolution|resolution]], screen colors, [[Cursor (computers)#Mouse cursor|pointers]] and screenmodes. The standard [[Intuition (Amiga)|Intuition interface]] is limited to [[color depth|display depths]] of [[8-bit computing|8 bits]], while RTG makes it possible to handle higher depths like [[24-bit]]s.

==== Sound ====
The sound chip, named Paula, supports four [[PCM]] sound channels (two for the left speaker and two for the right) with 8-bit resolution for each channel and a 6-bit volume control per channel. The analog output is connected to a low-pass filter, which filters out high-frequency aliasing when the Amiga is using a lower sampling rate (see [[Nyquist frequency]]). The brightness of the Amiga's power LED is used to indicate the status of the Amiga's low-pass filter. The filter is active when the LED is at normal brightness, and deactivated when dimmed (or off on older A500 Amigas). On Amiga 1000 (and first Amiga 500 and Amiga 2000 model), the power LED had no relation to the filter's status, and a wire needed to be manually soldered between pins on the sound chip to disable the filter. Paula can read arbitrary waveforms at arbitrary rates and amplitudes directly from the system's [[RAM]], using direct memory access (DMA), making sound playback without CPU intervention possible.

Although the hardware is limited to four separate sound channels, software such as ''[[OctaMED]]'' uses software mixing to allow eight or more virtual channels, and it was possible for software to mix two hardware channels to achieve a single 14-bit resolution channel by playing with the volumes of the channels in such a way that one of the source channels contributes the most significant bits and the other the least.

The quality of the Amiga's sound output, and the fact that sound hardware is part of the standard chipset and easily addressed by software, were standout features of Amiga hardware unavailable on IBM PC compatibles for years.{{efn|The [[Gravis UltraSound]] expansion card got released in 1992 and became the first on the PC platform to feature multiple sample sound channels (up to 32) mixed in hardware from its own RAM.}} Third-party sound cards exist that provide [[Digital signal processor|DSP]] functions{{citation needed|date=March 2021}}, multi-track [[direct-to-disk recording]]{{citation needed|date=March 2021}}, multiple hardware sound channels and 16-bit and beyond resolutions. A retargetable sound API called [[AHI (Amiga)|AHI]] was developed allowing these cards to be used transparently by the [[Operating system|OS]] and software.<ref>{{cite magazine |last=Březovský|first=Boleslav |url=http://amigareview.amiga.sk/amiga-review-24/ahi-audio-system|date=January 1997|title=AHI Audio System|language=Czech|magazine=Amiga Review|publisher=Atlantida Publishing|issn=1211-1465|issue=24|pages=18–19}}</ref>

=== Kickstart firmware ===
{{Main|Kickstart (Amiga)}}

Kickstart is the [[firmware]] upon which AmigaOS is [[booting|bootstrap]]ped. Its purpose is to initialize the Amiga hardware and core components of AmigaOS and then attempt to boot from a [[bootable]] [[volume (computing)|volume]], such as a floppy disk or hard disk drive. Most models (excluding the Amiga 1000) come equipped with Kickstart on an embedded [[Read-only memory|ROM-chip]].
There are various editions of Kickstart ROMs starting with Kickstart v1.1 for the Amiga 1000, v1.2 and v1.3 for the A500, Kickstart v2.1 on A500+, Kickstart v2.2 for A600 and dual ROMs for Kickstart v3.0 and 3.1 for A1200 and A4000. After Commodore's demise there have been new Kickstart v3.1 ROMs made available for both the A500 and A600 Computers. Amiga Software is mostly backward compatible, but v2.1 ROMs and newer differ slightly, which can cause software glitches with earlier programs. To help address this and to get earlier programs to work with later Kickstart ROMs, some tools have been produced such as RELOKIK 1.4 and MAKE IT WORK! for the A600 and A1200. They revert the system to temporarily boot in Kickstart v1.3.

=== Keyboard and mouse ===
[[File:Amiga Mouse.jpg|thumb|upright|left|Amiga mouse]]

The keyboard on Amiga computers is similar to that found on a mid-80s IBM PC: Ten function keys, a numeric keypad, and four separate directional arrow keys. [[Caps Lock]] and [[Control key|Control]] share space to the left of A. Absent are Home, End, Page Up, and Page Down keys: These functions are accomplished on Amigas by pressing shift and the appropriate arrow key. The Amiga keyboard adds a Help key, which a function key usually acts as on PCs (usually F1). In addition to the Control and Alt modifier keys, the Amiga has 2 "Amiga" keys, rendered as "Open Amiga" and "Closed Amiga" similar to the Open/Closed Apple logo keys on Apple II keyboards. The left is used to manipulate the operating system (moving screens and the like) and the right delivers commands to the application. The absence of Num lock frees space for more mathematical symbols around the numeric pad.

Like IBM-compatible computers, the mouse has two buttons, but in AmigaOS, pressing and holding the right button replaces the system [[status line]] at the top of the screen with a Maclike [[menu bar]]. As with Apple's [[Classic Mac OS|Mac OS]] prior to [[Mac OS 8]], menu options are selected by releasing the button over that option, not by left clicking. Menu items that have a Boolean toggle state can be left clicked whilst the menu is kept open with the right button, which allows the user – for example – to set some selected text to bold, underline and italics in one visit to the menus.

The mouse plugs into one of two [[Atari joystick port]]s used for [[joystick]]s, [[Paddle (game controller)|game paddles]], and [[graphics tablet]]s. Although compatible with [[analog stick|analog joystick]]s, Atari-style digital joysticks became standard.<ref name="anderson198710">{{cite news | url=https://archive.org/stream/1987-10-compute-magazine/Compute_Issue_089_1987_Oct#page/n17/mode/2up | title=Close Up: The Amiga 500 | work=Compute! | date=October 1987 | access-date=18 January 2015 | author=Anderson, Rhett | pages=16–19 | archive-url=https://web.archive.org/web/20141204185248/http://archive.org/stream/1987-10-compute-magazine/Compute_Issue_089_1987_Oct#page/n17/mode/2up | archive-date=4 December 2014 | url-status=live | df=dmy-all }}</ref> Unusually, two independent mice can be connected to the joystick ports; some games, such as [[Lemmings (video game)#Two-player mode|Lemmings]], were designed to take advantage of this.<ref>{{cite magazine|url=https://www.wired.com/2007/05/gallery-amiga0411|title=Top 10 Most Influential Amiga Games|magazine=[[Wired (magazine)|Wired]]|date=2007-05-11|access-date=2022-07-01|archive-url=https://web.archive.org/web/20220701033346/https://www.wired.com/2007/05/gallery-amiga0411/|archive-date=2022-07-01|url-status=live}}</ref>

=== Other peripherals and expansions ===
[[File:Amiga Sound Sampling Hardware.jpg|thumb|upright|8-bit sound sampling hardware for the Amiga]]

The Amiga was one of the first computers for which inexpensive sound sampling and video digitization accessories were available. As a result of this and the Amiga's audio and video capabilities, the Amiga became a popular system for editing and producing both music and video.

Many expansion boards were produced for Amiga computers to improve the performance and capability of the hardware, such as memory expansions, [[SCSI]] controllers, CPU boards, and graphics boards. Other upgrades include [[genlock]]s, network cards for [[Ethernet]], [[modem]]s, [[sound card]]s and samplers, [[Video capture|video digitizers]], extra [[serial port]]s, and [[Parallel ATA|IDE]] controllers. Additions after the demise of Commodore company are [[USB]] cards. The most popular upgrades were memory, SCSI controllers and CPU accelerator cards. These were sometimes combined into one device.

Early CPU accelerator cards used the full 32-bit CPUs of the 68000 family such as the [[Motorola 68020]] and [[Motorola 68030]], almost always with 32-bit memory and usually with [[Floating-point unit|FPUs]] and [[Memory management unit|MMUs]] or the facility to add them. Later designs feature the [[Motorola 68040]] or [[Motorola 68060]]. Both CPUs feature integrated FPUs and MMUs. Many CPU accelerator cards also had integrated SCSI controllers.

Phase5 designed the [[PowerUP (accelerator)|PowerUP]] boards ([[Blizzard PPC]] and [[PowerUP (accelerator)#Cyberstorm PPC|CyberStorm PPC]]) featuring both a 68k (a 68040 or 68060) and a PowerPC (603 or 604) CPU, which are able to run the two CPUs at the same time and share the system memory. The PowerPC CPU on PowerUP boards is usually used as a coprocessor for heavy computations; a powerful CPU is needed to run [[MAME]] for example, but even decoding [[JPEG]] pictures and [[MP3]] audio was considered heavy computation at the time. It is also possible to ignore the 68k CPU and run [[Linux]] on the PPC via project Linux APUS, but a PowerPC-native AmigaOS promised by Amiga Technologies GmbH was not available when the PowerUP boards first appeared.<ref name="AutoP5-9" />

24-bit graphics cards and video cards were also available. Graphics cards were designed primarily for 2D artwork production, workstation use, and later, gaming. Video cards are designed for inputting and outputting video signals, and processing and manipulating video.

In the North American market, the ''NewTek [[Video Toaster]]'' was a video effects board that turned the Amiga into an affordable video processing computer that found its way into many professional video environments. One well-known use was to create the special effects in early series of ''[[Babylon 5]]''.<ref>{{cite web |url=http://www.geek.com/games/cgi-first-introduced-to-tv-in-babylon-5-by-mit-presentor-771051/ |work=geek.com |title=CGI first introduced to TV in Babylon 5 by MIT presentor {{sic|nolink=y}} |access-date=2014-02-15 |archive-url=https://web.archive.org/web/20140222172408/http://www.geek.com/games/cgi-first-introduced-to-tv-in-babylon-5-by-mit-presentor-771051/ |archive-date=2014-02-22 |url-status=live }}</ref> Due to its [[NTSC]]-only design, it did not find a market in countries that used the [[PAL]] standard, such as in Europe. In those countries, the ''OpalVision'' card was popular, although less featured and supported than the Video Toaster. Low-cost [[Time base correction|time base correctors]] (TBC) specifically designed to work with the Toaster quickly came to market, most of which were designed as standard Amiga bus cards.

Various manufacturers started producing PCI busboards for the A1200, A3000 and A4000, allowing standard Amiga computers to use PCI cards such as graphics cards, [[Sound Blaster]] sound cards, 10/100 Ethernet cards, USB cards, and television tuner cards. Other manufacturers produced hybrid boards that contained an Intel x86 series chip, allowing the Amiga to emulate a PC.

PowerPC upgrades with Wide SCSI controllers, PCI busboards with Ethernet, sound and 3D graphics cards, and tower cases allowed the A1200 and A4000 to survive well into the late nineties.

Expansion boards were made by Richmond Sound Design that allow their [[show control]] and [[sound design]] software to communicate with their custom hardware frames either by ribbon cable or fiber optic cable for long distances, allowing the Amiga to control up to eight million digitally controlled external audio, lighting, automation, relay and voltage control channels spread around a large theme park, for example. See [[Amiga software]] for more information on these applications.

Other devices included the following:
* [[Amiga 500#Trap-door expansion 501|Amiga 501]] with 512&nbsp;KB RAM and [[real-time clock]]
* Trumpcard 500 [[Zorro-II]] SCSI interface
* [[Great Valley Products#GVP A530 Turbo|GVP A530 Turbo]], accelerator, RAM expansion, PC emulator
* A2091 / A590 SCSI hard disk controller + 2&nbsp;MB RAM expansion<ref name="amigahw_1161" /><ref name="amigahw_534" />
* A3070 SCSI tape backup unit with a capacity of {{nowrap|250 MB}}, [[OEM]] Archive Viper 1/4-inch<ref name="amigahw_1296" />
* A2065 Ethernet Zorro-II interface – the first Ethernet interface for Amiga; uses the [[AMD Am7990]] chip<ref name="amigahw_905" /><ref name="amigacx_a3000eth" /> The same interface chip is used in [[DECstation]] as well.
* Ariadne Zorro-II Ethernet interface using the AMD Am7990<ref name="amigacx_a3000eth" />
* A4066 Zorro II Ethernet interface using the SMC 91C90QF<ref name="amigacx_a3000eth" /><ref name="amigahu_a4066p1" /><!-- http://hardware.amiga.hu/exp/a4066 -->
* X-Surf from Individual Computers using the Realtek 8019AS<ref name="amigacx_a3000eth" />
* A2060 [[Arcnet]]<ref name="amigahi_netfaq_AmiTCP" />
* A1010 [[Floppy-disk controller|floppy]] disk drive consisting of a 3.5-inch [[double density]] (DD), {{nowrap|300 rpm}}, {{nowrap|250&nbsp;kbit/s}} drive unit connected via [[D-subminiature|DB-23]] connector; track-to-track delay is on the order of {{nowrap|~94 ms}}. The default capacity is {{nowrap|880 KB}}<!-- 80*2*11*512 = 901120 -->. Many clone drives were available, and products such as [[Individual Computers Catweasel|the Catweasel]] and [[KryoFlux]] make it possible to read and write Amiga and other special disc formats on standard x86 PCs.<ref name="AutoP5-10" />
* [[NE2000]]-compatible [[PC Card|PCMCIA]] Ethernet cards for Amiga 600 and Amiga 1200<ref name="AutoP5-11" />

==== Serial ports ====
The Commodore A2232 board provides seven RS-232C [[serial port]]s in addition to the Amiga's built-in serial port. Each port can be driven independently at speeds of 50 to {{nowrap|19,200 bits/s}}. There is, however, a driver available on [[Aminet]] that allows two of the serial ports to be driven at {{nowrap|115,200 bits/s}}.<ref name="bboah_a2232">{{cite web|title=Big Book of Amiga Hardware - Commodore: A2232|url=http://www.bboah.com/index.php?action=artikel&cat=58&id=2464&artlang=en|date=2009-01-25|access-date=2013-06-21|publisher=bboah.com|archive-url=https://web.archive.org/web/20131104033651/http://www.bboah.com/index.php?action=artikel&cat=58&id=2464&artlang=en|archive-date=2013-11-04|url-status=live}}</ref> The serial card used the [[65CE02]] CPU<ref name="bboah_a2232img">{{cite web|title=a2232_big.jpg|url=http://www.bboah.com/download_photos/a2232_big.jpg|date=2008-08-01|access-date=2013-06-21|publisher=bboah.com|archive-url=https://web.archive.org/web/20131104034054/http://www.bboah.com/download_photos/a2232_big.jpg|archive-date=2013-11-04|url-status=dead}}</ref> clocked at {{nowrap|3.58 MHz}}.<ref name="bboah_a2232"/> This CPU was also part of the [[CSG 65CE02|CSG 4510]] CPU core that was used in the [[Commodore 65]] computer.

==== Networking ====
Amiga has three networking interface APIs:
* AS225: the official Commodore TCP/IP stack [[API]] with hard-coded drivers in revision 1 (AS225r1) for the [[AMD Lance Am7990|A2065 Ethernet]] and the A2060 Arcnet interfaces.<ref name="amigahi_netfaq_AmiTCP" /> In revision 2, (AS225r2) the SANA-II interface was used.
* SANA-II: a standardized API for hardware of network interfaces. It uses an inefficient buffer handling scheme, and lacks proper support for [[Promiscuous mode|promiscuous]] and [[multicast]] modes.
* Miami Network Interface (MNI): an API that doesn't have the problems that SANA-II suffers from. It requires AmigaOS v2.04 or higher.

Different network media were used:

{| class="wikitable sortable"
|-
! Type !! Speed !! Example
|- <!-- ntsh template used with kbit/s -->
| [[Ethernet]]
| style="text-align:right;"| {{ntsh|10000}} {{nowrap|10,000&nbsp;kbit/s}}
| A2065<ref name="amigahw_905">{{cite web|title=Commodore: A2065 |url=http://www.amiga-hardware.com/showhardware.cgi?HARDID=905 |url-status=dead |archive-url=https://web.archive.org/web/20130120150722/http://www.amiga-hardware.com/showhardware.cgi?HARDID=905 |archive-date=2013-01-20 }} 090428 amiga-hardware.com</ref>
|-
| [[ARCNET]]
| style="text-align:right;"| {{ntsh|2500}} {{nowrap|2,500&nbsp;kbit/s}}
| A560,<ref name="amiga-hardware_com-showhardware_cgi_HARDID_903" /> A2060<ref name="amiga-hardware_com-showhardware_cgi_HARDID_904" />
|-
| [[Floppy disk controller]]
| style="text-align:right;"| {{ntsh|250}} {{nowrap|250&nbsp;kbit/s}}
| Amitrix: Amiga-Link<ref name="amiga-hardware_com-showhardware_cgi_HARDID_899" />
|-
| [[Serial port]]
| style="text-align:right;"| {{ntsh|115}} {{nowrap|≤ 115.2&nbsp;kbit/s}}
| [[RS-232]]
|-
| [[Parallel port]]
| style="text-align:right;"| {{ntsh|1600}} ≈1,600&nbsp;kbit/s<!-- educated guess -->{{original research inline|date=August 2012}}
| Village Tronic: Liana<ref name="amiga-hardware_com-showhardware_cgi_HARDID_1590" />
|-
| [[Token Ring]]
| style="text-align:right;"| {{ntsh|1500}} 1,500&nbsp;kbit/s
| Nine Tiles: AmigaLink (9 Tiles)<ref name="amiga-hardware_com-showhardware_cgi_HARDID_1436" />
|-
| [[AppleTalk]] / [[LocalTalk]]
| style="text-align:right;"| {{ntsh|230}} 230.4 – {{nowrap|460&nbsp;kbit/s}}
| PPS-Doubletalk<ref name="amiga-hardware_com-showhardware_cgi_HARDID_918" />
|}