Editing Amiga 500

{{Short description|Personal computer by Commodore}}
{{Use mdy dates|date=December 2020}}
{{Infobox computer
| name = Amiga 500
| logo = Commodore Amiga 500 logo.svg
| image = Amiga500 system.jpg
| caption = A500 with 1084S monitor and Amiga 1010 external second floppy drive
| developer = [[Commodore International]]
| family = [[Amiga]]
| type = [[Home computer]]
| release date = April 1987 ([[Netherlands]])<br />May 1987 (Europe)<br />October 1987 (US/UK)
| unitssold = 2.6 million<ref name="IM-OG"/><br>1,160,500 units in Germany (including Amiga 500 Plus sales)
| price<!--intro--> = {{unbulleted list|US{{Inflation|US|699|1987|fmt=eq|orig=yes|r=-1}}|{{Inflation|UK|499|1987|fmt=eq|orig=yes|cursign=£|r=-1}}}}
| discontinued = {{End date|1992}}
| media = 880&nbsp;[[Kilobyte|KB]] floppy disks
| os = [[AmigaOS]] v1.2 – 1.3 (upgradable to current version if enough RAM is installed)
| cpu = [[Motorola 68000]] @ {{nowrap|7.16 MHz ([[NTSC]])}}<br> {{nowrap|7.09 MHz ([[PAL]])}}
| memory = 512 or 1024&nbsp;[[Kilobyte|KB]] 150&nbsp;ns (maximum 9 to 138&nbsp;MB, depending on upgrades){{efn|name=binpre|Here, K, M, G, or T refer to the [[binary prefix]]es based on powers of 1024}}{{efn|Using existing hardware, an A500 can be expanded by an internal CPU board with up to 128&nbsp;MB like a [https://bigbookofamigahardware.com/bboah/product.aspx?id{{=}}67 DCE Viper 530], 8&nbsp;MB external Fast RAM, and 2&nbsp;MB Agnus expansion.}}
| graphics = [[Denise (computer chip)|Denise]]
| display = 736×567i 4&nbsp;[[Color depth|bpp]] ([[PAL]])<br/>736×483i 4&nbsp;bpp ([[NTSC]])<br/>368×567i 6&nbsp;bpp (PAL)<br/>368×483i 6&nbsp;bpp (NTSC)
| sound = 4× 8-bit channels [[Pulse-code modulation|PCM]] at max. {{nowrap|28 [[kHz]]}} with 6-bit volume in stereo
| predecessor = [[Amiga 1000]]
| successor = {{ubl|[[Amiga 500 Plus]]|[[Amiga 600]]}}
}}

The '''Amiga 500''', also known as the '''A500''', was the first popular version of the [[Amiga]] home computer, "redefining the home computer market and making so-called luxury features such as multitasking and colour a standard long before Microsoft or Apple sold these to the masses."<ref>{{cite web |url=http://www.bambi-amiga.co.uk/amigahistory/ahistory.html |title=The Twists and Turns of the Amiga Saga |access-date=July 26, 2023 |archive-date=July 26, 2023 |archive-url=https://web.archive.org/web/20230726024146/http://www.bambi-amiga.co.uk/amigahistory/ahistory.html |url-status=live }}</ref> It contains the same [[Motorola 68000]] as the [[Amiga 1000]], as well as the same graphics and sound coprocessors, but is in a smaller case similar to that of the [[Commodore 128]].

[[Commodore International|Commodore]] announced the Amiga 500 at the January 1987 winter [[Consumer Electronics Show]]{{snd}}at the same time as the high-end [[Amiga 2000]]. It was initially available in the Netherlands in April 1987, then the rest of Europe in May.<ref>{{Cite web|url=http://www.amigahistory.plus.com/sales.html|title=Commodore-Amiga Sales Figures|website=www.amigahistory.plus.com|access-date=February 4, 2020|archive-url=https://web.archive.org/web/20180927041337/http://www.amigahistory.plus.com/sales.html|archive-date=September 27, 2018|url-status=dead}}</ref> In North America and the UK it was released in October 1987 with a {{nowrap|US$699/£499}} list price. It competed directly against models in the [[Atari ST]] line.

The Amiga 500 was sold in the same retail outlets as the [[Commodore 64]], as opposed to the computer store-only Amiga 1000. It proved to be Commodore's best-selling model, particularly in Europe.<ref>{{cite web |author=Gareth Knight |url=http://www.amigau.com/aig/sales.html |title=Commodore-Amiga Sales Figures |publisher=amigau.com |website=www.amigau.com |access-date=July 24, 2013 |archive-url=https://web.archive.org/web/20090524012705/http://www.amigau.com/aig/sales.html |archive-date=May 24, 2009}}</ref> Although popular with hobbyists, arguably its most widespread use was as a gaming machine, where its graphics and sound were of significant benefit. It was followed by a revised version of the computer, the [[Amiga 500 Plus]], and the 500 series was discontinued in 1992.

== Releases ==
In mid-1988, the Amiga 500 dropped its price from [[Pound sterling|£]]499 to £399,<ref>https://amr.abime.net/issue_535_pages page 7</ref> and it was later bundled with the ''Batman Pack'' in the United Kingdom (from October 1989 to September 1990) which included the games [[Batman (1989 video game)|''Batman'']], ''[[F/A-18 Interceptor]]'', [[The NewZealand Story|''The New Zealand Story'']] and the bitmap graphics editor [[Deluxe Paint|Deluxe Paint 2]].<ref>{{cite web| url=http://www.amigahistory.plus.com/a500batman.html |title=A500 Batman Pack |archive-url=https://web.archive.org/web/20200327045916/http://www.amigahistory.plus.com/a500batman.html |archive-date=27 March 2020 |website=Amiga History Guide}}</ref> Also included was the [[Amiga video connector]] which allows the A500 to be used with a conventional CRT television.

In November 1991, the enhanced [[Amiga 500 Plus]] replaced the 500 in some markets. It was bundled with the ''Cartoon Classics'' pack in the United Kingdom at £399, although many stores still advertised it as an 'A500'.<ref>{{cite web |author=Gareth Knight |url=http://www.amigahistory.co.uk/cartoon.html |title=Cartoon Classics Bundles |website=Amigahistory.co.uk |date=October 21, 2002 |access-date=July 24, 2013 |archive-date=November 21, 2010 |archive-url=https://web.archive.org/web/20101121042931/http://www.amigahistory.co.uk/cartoon.html |url-status=live }}</ref> The Amiga 500 Plus was virtually identical except for its new operating system, integrated 1MB of Chip memory, different 'trap-door' expansion slot and slightly different keyboard, and in mid-1992, the two were discontinued and effectively replaced by the [[Amiga 600]].<ref>{{cite magazine|url=https://archive.org/details/amigashopper-magazine-15|title=End of the line for A500|last=Storer|first=Andy|magazine=Amiga Shopper|publisher=[[Future Publishing]]|date=July 1992|access-date=November 24, 2021|issue=15|pages=7–8|issn=0961-7302}}</ref> In late 1992, Commodore released the [[Amiga 1200]], a machine closer in concept to the original Amiga 500, but with significant technical improvements. Despite this, neither the A1200 nor the A600 replicated the commercial success of its predecessor. By this time, the home market was strongly shifting to [[IBM PC compatible]]s with [[Video Graphics Array|VGA]] graphics and the low-cost [[Macintosh Classic]], [[Macintosh LC|LC]], and [[Macintosh IIsi|IIsi]] models.<ref>{{cite web |author=Gareth Knight |url=http://www.amigahistory.co.uk/commodore.html |title=Commodore History |website=Amigahistory.co.uk |access-date=July 24, 2013 |archive-date=August 30, 2013 |archive-url=https://web.archive.org/web/20130830090142/http://www.amigahistory.co.uk/commodore.html |url-status=live }}</ref>

== Description ==
Outwardly resembling the [[Commodore 128]]<ref name="byte198706">{{cite news | url=https://archive.org/stream/byte-magazine-1987-06/1987_06_BYTE_12-06_CAD_Mice_12-MHz_ATs_IBM_PS2_Family#page/n55/mode/2up | title=Low-End Amiga | work=BYTE | date=June 1987 | access-date=November 5, 2013 | pages=52}}</ref> and codenamed "[[Rock Lobster]]" during development,<ref>{{cite web |url=http://www.amigahistory.co.uk/b52board.html |title=Mystery Motherboards |author=<!--Not stated--> |date=2002-08-03 |website=amiga history guide |publisher= |archive-url=https://web.archive.org/web/20110208214625/http://www.amigahistory.co.uk/b52board.html |access-date=2022-06-17 |archive-date=February 8, 2011 |quote=Everything George Robbins worked on was some reference to the B-52's.}}</ref> the Amiga 500's base houses a keyboard and a CPU in one shell, unlike the [[Amiga 1000]]. The keyboard for Amiga 500s sold in the United States contains 94 keys, including ten [[function key]]s, four cursor keys, and a number pad. All European versions the keyboard have an additional two keys, except for the British variety, which still uses 94 keys.{{Sfn|Technical Reference Manual|1987|p=2}} It uses a Motorola 68000 microprocessor running at {{val|7.15909 |ul=MHz}} in [[NTSC]] regions and {{val|7.09379 |u=MHz}} in [[PAL]] regions.{{Sfn|Technical Reference Manual|1987|pp=45–46}} The CPU implements a 32-bit model and has 32-bit registers, but it has a 16-bit main [[Arithmetic logic unit|ALU]] and uses a 16-bit external data bus and a 24-bit address bus, providing a maximum of 16&nbsp;MB of [[address space]].{{efn|name=binpre}}{{Sfn|Greenley|Green|Baker|1991|p=2}}{{Sfn|Technical Reference Manual|1987|p=90}} Also built in to the base of the computer is a {{frac|3|1|2}}-inch floppy disk drive. The user can also install up to three external floppy drives, either {{frac|3|1|2}}- or {{frac|5|1|4}}-inch, via the disk drive port. The second and third additional drives are installed by [[Daisy chain (electrical engineering)|daisy-chaining]] them. Supported by these drives are double-sided disks with a capacity of 901,120 bytes, as well as 360- and 720-KB disks formatted for IBM PC compatibles.{{Sfn|Greenley|Green|Baker|1991|p=6, 335}}

The earliest Amiga 500 models use nearly the same [[Original Amiga chipset]] as the Amiga 1000.{{efn|Agnus was enhanced to control up to {{val|1|ul=MB}}{{efn|name=binpre}} [[random-access memory|RAM]] and glue logic was integrated into [[Amiga custom chips#Gary|Gary]] to reduce costs.}} So graphics can be displayed in multiple resolutions and color depths, even on the same screen. Resolutions vary from 320×200 (up to 32 colors) to 640×400 (up to 16 colors) for NTSC (704×484 overscan) and 320×256 to 640×512 for PAL (704×576 overscan.)<ref name="displaysize">{{cite book|last1 = Peck|first1 = Robert|last2 = Deyl|first2 = Susan|last3 = Miner|first3 = Jay|last4 = Raymond|first4 = Chris|title = Amiga hardware reference manual|publisher = [[Addison Wesley]]|date=September 1986|page = 72|isbn = 0-201-11077-6}}</ref> The system uses [[planar (computer graphics)|planar]] graphics, with up to five bitplanes (four in high resolution) allowing 2-, 4-, 8-, 16-, and 32-color screens, from a palette of 4096 colors. Two special graphics modes are also available: Extra HalfBrite, which uses a sixth bitplane as a mask to cut the brightness of any pixel in half (resulting in 32 arbitrary colors plus 32 more colors set at half the value of the first 32), and [[Hold-And-Modify]] (HAM) which allows all 4096 colors to be used on screen simultaneously.<ref name=bitplanes>{{harvnb|Peck|Deyl|Miner|Raymond|1986|p=37}}</ref> Later revisions of the chipset are [[PAL]]/[[NTSC]] switchable in software.

The sound chip produces four hardware-mixed channels, two to the left and two to the right, of 8-bit PCM at a sampling frequency up to {{val|28 |ul=kHz}}. Each hardware channel has its own independent volume level and sampling rate, and can be designated to another channel where it can modulate both volume and frequency using its own output. With [[Direct memory access|DMA]] disabled it's possible to output with a sampling frequency up to {{val|56 |u=kHz}}. There is a common trick to [[Original Chip Set#Audio|output sound with 14-bit precision]] that can be combined to output 14-bit {{val|56 |u=kHz}} sound.<ref>{{Cite web |url=http://aminet.net/package/mus/play/Play16 |title=Aminet: mus/play/Play16.lha |date=November 9, 2003 |website=aminet.net |access-date=February 16, 2016 |archive-url=https://web.archive.org/web/20200320173308/http://aminet.net/package/mus/play/Play16 |archive-date=March 20, 2020 |url-status=dead }}</ref>

The stock system comes with [[AmigaOS]] version 1.2 or 1.3 and {{val|512 |u=KB}}{{efn|name=binpre}} of [[Amiga Chip RAM|chip RAM]] (150 ns access time), one built-in double-density [[floppy disk drive|standard floppy disk drive]] that is completely programmable and can read {{val|720 |u=KB}} [[IBM PC]] disks, {{val|880 |u=KB}} standard Amiga disks, and up to {{nowrap|984 KB}} using custom-formatting drivers.

Despite the lack of [[Amiga Zorro II|Amiga 2000-compatible internal expansion slots]], there are many ports and expansion options. There are two [[D-subminiature|DE9M]] [[Atari joystick port]]s for [[joystick]]s or [[mouse (computing)|mice]], and stereo audio [[RCA connector]]s (1&nbsp;V [[peak-to-peak|p-p]]). There is a floppy drive port for daisy-chaining up to three extra floppy disk drives via a DB23F connector.<ref name="gbwxgm">{{cite web|website=amigahardware.mariomisic.de|title=Hi Res Version, Rear of Amiga 500 – 122K|url=http://amigahardware.mariomisic.de/download_photos/a500_4_big.jpg|access-date=July 27, 2007|archive-date=August 9, 2007|archive-url=https://web.archive.org/web/20070809235410/http://amigahardware.mariomisic.de/download_photos/a500_4_big.jpg|url-status=live}} 070728 amigahardware.mariomisic.de</ref> The then-standard [[RS-232]] serial port (DB25M) and [[Centronics]] [[parallel port]] (DB25F) are also included. The power supply is ({{val|+5|u=V}}, {{val|p=±|12|u=V}}).<ref name=itgehi>{{cite web|website=www.ntrautanen.fi|title=Amiga 500/600/1200 Power Connector|url=http://www.ntrautanen.fi/computers/hardware/misc/a500_power.htm|access-date=August 8, 2007|archive-url=https://web.archive.org/web/20070927010556/http://www.ntrautanen.fi/computers/hardware/misc/a500_power.htm|archive-date=September 27, 2007|url-status=dead}} 070808 ntrautanen.fi</ref> 
The system displays video in analog [[component video|RGB]] {{val|50 |ul=Hz}} PAL or {{val|60 |u=Hz}} NTSC through a proprietary DB23M connector and in NTSC mode the line frequency is {{val|15.75 |u=kHz}} [[synchronization|HSync]] for standard video modes, which is compatible with NTSC television and CVBS/RGB video, but out of range for most [[video graphics array|VGA]]-compatible monitors, while a [[multisync monitor]] is required for some of the higher resolutions. This connection can also be [[genlock]]ed to an external video signal. The system was bundled with an [[RF modulator|RF adapter]] to provide output on televisions with a coaxial RF input, while monochrome video is available via an [[RCA connector]] (also coaxial). On the left side, behind a plastic cover, there is a Zorro (Zorro I) bus expansion external edge connector with 86 pins. Peripherals such as a hard disk drive can be added via the expansion slot and are configured automatically by the Amiga's [[AutoConfig]] standard, so that multiple devices do not conflict with each other. Up to {{val|8 |u=MB}}{{efn|name=binpre}} of so-called "fast RAM" (memory that can be accessed by the CPU only) can be added using the side expansion slot. This connector is electronically identical with the Amiga 1000's, but swapped on the other side.

The Amiga 500 has a "trap-door" slot on the underside for a RAM upgrade (typically {{val|512 |u=KB}}){{efn|name=binpre}}. This extra RAM is classified as "fast" RAM, but is sometimes referred to as "slow" RAM: due to the design of the expansion bus, it is actually on the chipset bus. Such upgrades usually include a battery-backed [[real-time clock]]. All versions of the A500 can have the additional RAM configured as chip RAM by a simple hardware modification, which involves fitting a later model (8372A) [[MOS Technology Agnus|Agnus]] chip. Likewise, all versions of the A500 can be upgraded to {{val|2 |u=MB}}{{efn|name=binpre}} chip RAM by fitting the {{nowrap|8372B Agnus}} chip and adding additional memory.

The Amiga 500 also sports an unusual feature for a budget machine, socketed chips, which allow easy replacement of defective chips. The CPU can be directly upgraded on the motherboard to a [[Motorola 68010|68010]]; or to a [[Motorola 68020|68020]], [[Motorola 68030|68030]], or [[Motorola 68040|68040]] via the side expansion slot; or by removing the CPU and plugging a CPU expansion card into the CPU socket (this requires opening the computer and thus voided any remaining warranty). In fact, all the custom chips can be upgraded to the [[Amiga Enhanced Chip Set]] (ECS) versions.

The plastic case is made of [[acrylonitrile butadiene styrene]], or ABS. ABS degrades with time due to exposure to oxygen, causing a yellowing of the case. Other factors contributing to the degradation and yellowing include heat, shear, and ultraviolet light. The yellowing can be reversed by using an [[optical brightener]], though without [[Stabilizer (chemistry)|stabilizing agents]] or antioxidants to block oxygen, the yellowing will return.<ref>{{cite web|url=https://www.theguardian.com/technology/blog/2009/mar/04/gadgets|title=What does it take to clean my old computer?|last=Johnson|first=Bobbie|work=[[The Guardian]]|date=March 4, 2009|access-date=November 24, 2021|archive-url=https://web.archive.org/web/20211124094207/https://www.theguardian.com/technology/blog/2009/mar/04/gadgets|archive-date=November 24, 2021|url-status=live}}</ref><ref>{{cite book|title=Plastics Additives: An A-Z reference|last=Pritchard|first=Geoffrey|series=Polymer Science and Technology Series |publisher=[[Springer Science+Business Media]]|date=1998|volume=1 |pages=55–56, 472–473|doi=10.1007/978-94-011-5862-6|isbn=978-94-011-5862-6}}</ref>

== Technical specifications ==
[[File:Amiga 1.3 and disks.jpg|thumb|right|The standard Amiga 500 requires floppies to boot.]]

* [[Original Amiga chipset|OCS]] (1.2 and 1.3 models) or [[Amiga Enhanced Chip Set|ECS]] (1.3 and 500+ 2.04 models) chipset. ECS revisions of the chipset made [[PAL]]/[[NTSC]] mode switchable in software.
** Sound: 4 hardware-mixed channels of 8-bit sound at up to {{nowrap|28 kHz}}.<ref>{{cite web |title=Amiga 500 |website=www.old-computers.com |url=http://www.old-computers.com/MUSEUM/computer.asp?c=65&st=1 |access-date=December 15, 2009 |archive-url=https://web.archive.org/web/20100330022140/http://www.old-computers.com/MUSEUM/computer.asp?st=1&c=65| archive-date=March 30, 2010 }}</ref> The hardware channels have independent volumes (65 levels) and sampling rates, and are mixed down to two fully left and fully right stereo outputs. A software controllable low-pass audio filter is also included.
* 512&nbsp;KB{{efn|name=binpre}} of chip RAM (150&nbsp;ns access time)
* [[AmigaOS]] 1.2 or 1.3 (upgradeable up to 3.1.4<ref>{{cite web |title=AmigaOS 3.1.4 on A500 |website=amigax1000.blogspot.com |date=December 15, 2018 |url=http://amigax1000.blogspot.com/2018/12/amigaos-314-on-a500.html |access-date=September 3, 2019 |archive-date=July 26, 2019 |archive-url=https://web.archive.org/web/20190726090428/http://amigax1000.blogspot.com/2018/12/amigaos-314-on-a500.html |url-status=live }}</ref> if 2&nbsp;MB{{efn|name=binpre}} of RAM are installed)
* One 3.5" double-density [[floppy disk drive]] is built in, which is completely programmable and thus can read {{nowrap|720 KB}} [[IBM PC]] disks, {{nowrap|880 KB}} standard Amiga disks, and up to {{nowrap|984 KB}} with custom formatting (such as Klaus Deppich's diskspare.device). Uses {{nowrap|300 rpm}} (5 rotations/second) and {{nowrap|250 kbit/s}}.
* Built-in keyboard
* A two-button mouse is included.

=== Graphics ===
* [[PAL]] mode: 768×580 maximum ([[overscan]] [[Interlaced video|interlaced]] if viewed on [[composite monitor]]/TV).<ref>{{Cite web |date=1990 |title=NewTek DigiView Gold Advert |url=http://amiga.resource.cx/adcoll/adcoll.pl?id=digiviewgold&pg=9 |access-date=2023-04-12 |website=Amiga Hardware Database |archive-date=January 28, 2023 |archive-url=https://web.archive.org/web/20230128095808/http://amiga.resource.cx/adcoll/adcoll.pl?id=digiviewgold&pg=9 |url-status=live }}</ref> Typical resolutions: 320×256, 640×256 or 640×512 (all displayed with borders).<ref name="amiga.lychesis.net">{{Cite web |title=Amiga Graphics Archive – Amiga Graphics Archive |url=http://amiga.lychesis.net/knowledge/ScreenModes.html |access-date=September 24, 2016 |archive-date=September 27, 2016 |archive-url=https://web.archive.org/web/20160927032905/http://amiga.lychesis.net/knowledge/ScreenModes.html |url-status=live }}</ref> 
* [[NTSC]] mode: 768×484 maximum (overscan interlaced if viewed on composite monitor/TV).<ref>{{Cite web |date=1989 |title=NewTek DigiView Gold advert |url=http://amiga.resource.cx/adcoll/adcoll.pl?id=digiviewgold&pg=5 |access-date=2023-04-12 |website=Amiga Hardware Database |archive-date=January 28, 2023 |archive-url=https://web.archive.org/web/20230128091703/http://amiga.resource.cx/adcoll/adcoll.pl?id=digiviewgold&pg=5 |url-status=live }}</ref> Typical resolutions: 320×200, 640×200 or 640×400 (all displayed with borders).<ref name="amiga.lychesis.net" /> 
* Graphics can be of arbitrary dimensions, resolution and colour depth, even on the same screen. The Amiga can show multiple resolution modes at the same time, splitting the screen vertically.
* [[Planar (computer graphics)|Planar]] graphics are used, with up to five bitplanes (four in hires); this allowed 2, 4, 8, 16 and 32 colour screens, from a palette of 4096 colours. 
* Two special graphics modes are also included: 
** [[Amiga Halfbrite mode|Extra Half Brite]] (EHB), which uses a sixth bitplane as a mask that halved the brightness of any colour seen
** [[Hold-And-Modify]] (HAM), which allows all 4096 colours on screen at once. HAM makes it possible to use {{nowrap|12 bpp}} over a {{nowrap|3 [[pixel]]}} wide span. This works by letting each pixel position use the previous RGB value and modify one of the red, green or blue values to a new 4-bit value. This will cause some negligible colour artifacts however.

=== Memory ===
Using various expansion techniques, the A500's total RAM can reach up to 138&nbsp;MB – 2&nbsp;MB Chip RAM, 8&nbsp;MB 16-bit Fast RAM, and 128&nbsp;MB 32-bit Fast RAM.{{efn|name=binpre}}

==== Chip RAM ====
The stock 512&nbsp;KB Chip RAM can be complemented by 512&nbsp;KB using a "trapdoor" expansion (Commodore A501 or compatible).{{efn|name=binpre}} While that expansion memory is connected to the chip bus, hardware limitations of early stock Agnus chip revisions prevent its use as Chip RAM, only the CPU can access it. Suffering from the same contention limitations as Chip RAM, that memory is known as "Slow RAM" or "Pseudo-fast RAM". Agnus revisions shipped with late A500 are [[Amiga Enhanced Chip Set|ECS]] and allow use of trapdoor RAM as real Chip RAM for a total 1&nbsp;MB.{{efn|name=binpre}} 

Additionally, several third-party expansions exist with up to 2&nbsp;MB{{efn|name=binpre}} on the trapdoor board. Using a [[Amiga custom chips#Gary|Gary]] adapter, that memory will be mapped as either split on Chip RAM and Slow RAM or fully as Slow RAM, depending on configuration.

Furthermore, using an [[Amiga 3000|A3000]] Agnus on an adapter board, it is possible to expand the Chip RAM to 2&nbsp;MB, matching the A500+.{{efn|name=binpre}}

==== Fast RAM ====
"Fast" RAM is located on the CPU-side bus. Its access is exclusive to the CPU and not slowed by any chipset access. The side expansion port allows for up to 8&nbsp;MB{{efn|name=binpre}} of [[Zorro II|Zorro-style]] expansion RAM. Alternatively, a CPU adapter allows for internal expansion.

==== Accelerator RAM ====
Internal or external CPU accelerators often include their own expansion memory. 16-bit CPUs are limited by the 24-bit address space but they can repurpose otherwise unused memory space for their included RAM. 32-bit CPU accelerators aren't limited by 24-bit addressing and can include up to 128&nbsp;MB{{efn|name=binpre}} of Fast RAM (and potentially more).

==== Memory map ====
{| class="wikitable"
|+Amiga system memory map{{Sfn|Greenley|Green|Baker|1991|p=314}}<ref>{{cite web | url=http://oscomp.hu/depot/amiga_memory_map.html | title=Amiga memory map | access-date=August 12, 2023 | archive-date=August 12, 2023 | archive-url=https://web.archive.org/web/20230812110419/http://oscomp.hu/depot/amiga_memory_map.html | url-status=live }}</ref>
|-
! Address    || Size in KB{{efn|name=binpre}} || Description
|-
|align="right"| 0x00 0000 <!--0x0003FFFF-->
|align="right"| 256 || Chip RAM
|-
|align="right"| 0x04 0000 <!--0x0007FFFF-->
|align="right"| 256 || Chip RAM ([[Amiga 1000|A1000]] option card)
|-
|align="right"| 0x08 0000 <!--0x000FFFFF-->
|align="right"| 512 || Chip RAM expansion
|-
|align="right"| 0x10 0000 <!--0x001FFFFF-->
|align="right"| 1024 || Extended Chip RAM for [[Amiga Enhanced Chip Set|ECS]]/[[Amiga Advanced Graphics Architecture|AGA]]
|-
|align="right"| 0x20 0000 <!--0x009FFFFF-->
|align="right"| 8192 || Primary auto-config space (Fast RAM)
|-
|align="right"| 0xA0 0000 <!--0x00BEFFFF-->
|align="right"| 1984 || Reserved
|-
|align="right"| 0xBF D000 <!--0x00BFDF00-->
|align="right"| 3.8 || [[MOS Technology CIA|8520-B]] (even-byte addresses)
|-
|align="right"| 0xBF E001 <!--0x00BFEF01-->
|align="right"| 3.8 || 8520-A (odd-byte addresses)
|-
|align="right"| 0xC0 0000 <!--0x00D7FFFF-->
|align="right"| 1536 || Internal expansion memory (pseudo-fast, "slow" RAM on Amiga 500)
|-
|align="right"| 0xD8 0000 <!--0x00DBFFFF-->
|align="right"| 256 || Reserved
|-
|align="right"| 0xDC 0000 <!--0x00DCFFFF-->
|align="right"| 64 || [[Real-time clock|Real time clock]]
|-
|align="right"| 0xDD 0000 <!--0x00DFEFFF-->
|align="right"| 188 || Reserved
|-
|align="right"| 0xDF F000 <!--0x00DFFFFF-->
|align="right"| 4 || Custom chip registers
|-
|align="right"| 0xE0 0000 <!--0x00E7FFFF-->
|align="right"| 512 || Reserved
|-
|align="right"| 0xE8 0000 <!--0x00E8FFFF-->
|align="right"| 64 || [[Amiga Zorro II|Zorro II]] auto-config space (before relocation)
|-
|align="right"| 0xE9 0000 <!--0x00EFFFFF-->
|align="right"| 448 || Secondary auto-config space (usually 64K I/O boards)
|-
|align="right"| 0xF0 0000 <!--0x00F7FFFF-->
|align="right"| 512 || 512K System ROM (reserved for extended ROM image e.g. CDTV or CD<sup>32</sup>)
|-
|align="right"| 0xF8 0000 <!--0x00FBFFFF-->
|align="right"| 256 || 256K System ROM ([[Kickstart (Amiga)|Kickstart]] 2.04 or higher)<!-- According to the linked wikipage, contradicts "ntrautanen_fi-amiga_memory" -->
|-
|align="right"| 0xFC 0000 <!--0x00FFFFFF-->
|align="right"| 256 || 256K System ROM
|}

=== Connectors ===
[[File:AMIGA500-3.jpg|thumb|290px|Backside of the base of the Amiga 500. From left to right, it features two [[Atari joystick port]]s, two audio connectors, a floppy drive port, a serial and a parallel port, a power input, and two separate inputs for RGB and monochrome monitors.{{Sfn|Introduction to the Amiga 500|1987|p=2-1}}]]
[[File:Amiga_520_1.jpg|thumb|right|The Amiga 520 adapter allows for an [[RF modulator|RF modulated]] output to be connected to a TV, or composite output to a monitor.]]

* Two [[Atari joystick port]]s for [[joystick]]s or [[Mouse (computing)|mice]]
* Stereo audio [[RCA connector]]s ({{val|1|u=V}} [[Peak-to-peak|p-p]])
* A floppy drive port (DB23F), for daisy-chaining up to 3 extra floppy disk drives via a [[D-subminiature|DB23F]] connector<ref name="gbwxgm"/>
* A standard [[RS-232]] serial port (DB25M)
* A [[parallel port]] (DB25F)
* Power inlet ({{val|+5 |u=V}}, {{val|p=±|12 |u=V}})<ref name = "itgehi" />
* [[Amiga video connector]]: Analogue [[RGB color model|RGB]] {{val|50|ul=Hz}} PAL and {{val|60 |u=Hz}} NTSC video output, provided on an Amiga-specific [[DB23]]M connector. Can drive video with {{val|15.75 |u=kHz}} [[Horizontal sync|HSync]] for standard Amiga video modes. This is not compatible with most [[Video Graphics Array|VGA]] monitors. A [[Multisync monitor]] is required for some higher resolutions. This connection can also be [[genlock]]ed to an external video signal. An [[RF modulator|RF adapter]] (A520) was frequently bundled with the machine to provide output on regular televisions or on [[composite video|composite]] monitors. A digital 16 colour Red-Green-Blue-Intensity signal is available too on the same connector.
* Monochrome video via an [[RCA connector]]
* [[Zorro II]] bus expansion on the left side behind a plastic cover
* Trapdoor slot under the machine, for RAM expansion and [[real-time clock]]

=== Expansions ===
* Expansion ports are limited to a side expansion port and a trapdoor expansion on the underside of the machine. The casing can also be opened up (voiding the warranty), all larger chips are socketed rather than being [[Through-hole technology|TH]]/[[Surface Mount Device|SMD]] soldered directly to the motherboard, so they can be replaced by hand.
* The CPU can be upgraded to a Motorola 68010 directly or to a 68020, 68030 or 68040 via the side expansion slot or a CPU socket adapter board.
* The chip RAM can be upgraded to {{nowrap|1 MB}}{{efn|name=binpre}} directly on the motherboard, provided a [[Fat Agnus]] chip is also installed to support it.
* Likewise, all the custom chips can be upgraded to the [[Extended chip set|ECS]] chipset.
* The A500+ model instead allowed upgrading by {{nowrap|1 MB}}{{efn|name=binpre}} trapdoor chip RAM without clock, but there was no visible means on board to map any of this as FAST, causing incompatibility with some stubbornly coded programs.
* There were modification instructions available for the A500 to solder or socket another {{nowrap|512 KB}} RAM on the board, then run extra address lines to the trapdoor slot to accommodate an additional {{nowrap|1 MB}} of fast or chip RAM depending on the installed chipset.{{efn|name=binpre}}
* Up to {{nowrap|8 MB}}{{efn|name=binpre}} of "fast RAM" can be added via the side expansion slot, even more if an [[Hardware acceleration|accelerator]] with a non-EC (without reduced data/address bus) processor and 32-bit RAM is used.
* Hard drive and other peripherals can be added via the side expansion slot.
* Several companies provided combined CPU, memory and hard drive upgrades{{snd}}or provided chainable expansions that extended the bus as they were added{{snd}}as there is only one side expansion slot.
* Expansions are configured automatically by [[AutoConfig]] software, so multiple pieces of hardware did not conflict with each other.

===Diagnostics===
When the computer is powered on a self-diagnostic test is run that will indicates failure with a specific colour:

#{{background color|#00B300|&nbsp;&nbsp;}} Medium green means chip RAM is not found or is damaged.
#{{background color|darkred|&nbsp;&nbsp;}} Red means bad [[Kickstart (Amiga)|kickstart]]-[[Read-only memory|ROM]].
#{{background color|yellow|&nbsp;&nbsp;}} Yellow means the [[central processing unit|CPU]] has crashed (no trap routine or trying to run bad code) or a bad [[Amiga Zorro II|Zorro]] [[expansion card]].<ref>[http://eab.abime.net/showthread.php?t=497 abime.net – Question blinking power LED/no screen on Amiga 500] read November 3, 2011</ref>
#{{background color|blue|&nbsp;&nbsp;}} Blue means a custom chip problem ([[Denise (OCS)|Denise]], [[Paula (computer chip)|Paula]], or [[Original Chip Set#Agnus|Agnus]]).
#{{background color|lime|&nbsp;&nbsp;}} Light green means [[MOS Technology CIA|CIA]] problem.
#{{background color|silver|&nbsp;&nbsp;}} Light gray means that the CIA might be defective.
#{{nowrap|{{background color|black|&nbsp;}} {{background color|black|&nbsp;}} Black and white stripes}}<!--verify?--> mean there is a ROM or [[MOS Technology CIA|CIA]] problem.
#{{background color|black|&nbsp;&nbsp;}} Black-only (no video) means there is no video output.<ref name=a3b>[http://amiga.serveftp.net/A3000_HardwareGuide/booting-problems.html amiga.serveftp.net – A3000 Booting Problems] {{Webarchive|url=https://web.archive.org/web/20120425132759/http://amiga.serveftp.net/A3000_HardwareGuide/booting-problems.html |date=April 25, 2012 }} read November 3, 2011</ref>

The keyboard [[light-emitting diode|LED]] uses blink codes:

#One blink means the keyboard ROM has a checksum error.
#Two blinks means RAM failure.
#Three blinks means watchdog timer failure.<ref name=a3b/>
'''<big>Measurements</big>'''

Overall (base): 6.2 cm x 47.4 cm x 33 cm; 2 7/16 in x 18 11/16 in x 13 in. <ref>{{Cite web |title=Commodore Amiga 500 Personal Computer |url=https://americanhistory.si.edu/collections/search/object/nmah_834010 |access-date=2023-09-27 |website=National Museum of American History |language=en |archive-date=September 12, 2023 |archive-url=https://web.archive.org/web/20230912221548/https://americanhistory.si.edu/collections/search/object/nmah_834010 |url-status=live }}</ref>

== Trap-door expansion 501 ==
{{Unsourced section|date=June 2023}}
[[File:RAM 512K for Amiga 500 ubt.jpeg|thumb|An A501 compatible expansion]]

A popular expansion for the Amiga 500 was the Amiga 501 circuit board that can be installed underneath the computer behind a plastic cover. The expansion contains {{nowrap|512 KB}} RAM configured by default as "[[Amiga Chip RAM#Fast RAM|Slow RAM]]" or "trap-door RAM" and a battery-backed [[real-time clock]] (RTC).

The 512 KB trap-door RAM and 512 KB of original chip RAM will result in 1 MB of total memory.{{efn|name=binpre}} The added memory is known as "Slow RAM", as its access is impacted by chip-bus bandwidth contention, while the chipset is not actually able to address it.

Later revisions of the motherboard provide solder-jumpers to relocate the trap-door RAM to the chip memory pool, given the [[MOS Technology Agnus|Agnus]] chip is the newer ECS version, shipped in later A500 motherboards. Newest (rev 8) A500s would share motherboard with A500+, and configure the expansion memory as CHIP by default.

== Software ==
{{Expand section|date=November 2021}}
Each time the Amiga 500 is booted, it executes code from the [[Kickstart (Amiga)|Kickstart]] ROM. The Amiga 500 initially came shipped with [[AmigaOS]] 1.2, but units since October 1988 had version 1.3 installed.{{Sfn|Technical Reference Manual|1987|p=1}}<ref>{{cite magazine|url=https://archive.org/details/AmigaMagazin198812|title=Aktuell|language=German|trans-title=Currently|last=Göckel|first=Michael|magazine=Amiga Magazin|publisher=[[Markt & Technik]]|date=December 1998|access-date=November 25, 2021|page=12|issn=0933-8713}}</ref>

== Reception and sales ==
The Amiga 500 was the best-selling model in the Amiga family of computers. The German computer magazine ''[[Chip (magazine)|Chip]]'' awarded the model the annual "Home Computer of the Year" title three consecutive times.<ref>{{cite book|url=https://archive.org/details/hoovershandbooko00hoov_4|url-access=registration|title=Hoover's Handbook of American Business 1993|last1=Hoover|first1=Gary|last2=Campbell|first2=Alta|publisher=The Reference Press|date=November 19, 2021|page=207|isbn=978-1-878753-03-8}}</ref> At the [[European Computer Trade Show]] 1991, it also won the Leisure Award for the similar "Home Computer of the Year" title.<ref>{{cite magazine|url=https://books.google.com/books?id=88LaAAAAMAAJ&q=%22Amiga+500%22+%22computer+of+the+year%22|title=European Computer Leisure Awards 1991|magazine=[[Compute!]]|date=September 1991|access-date=November 19, 2021|volume=13|issue=9|page=6}}</ref> 

Owing to the inexpensive cost of the Amiga 500 in then price-sensitive Europe, sales of the Amiga family of computers were strongest there, constituting 85 percent of Commodore's total sales in the fourth quarter of 1990. The Amiga 500 was widely perceived as a gaming machine and the Amiga 2000 a computer for artists and hobbyists.{{Sfn|Maher|2018|pp=178–180}} 

It has been claimed<ref>{{cite web|url=https://www.eurogamer.net/articles/2015-07-23-the-amiga-is-30-years-old-today|title=The Amiga is 30 years old today|last=Yin-Poole|first=Wesley|work=[[Eurogamer]]|date=July 23, 2015|access-date=November 19, 2021|archive-date=November 19, 2021|archive-url=https://web.archive.org/web/20211119014802/https://www.eurogamer.net/articles/2015-07-23-the-amiga-is-30-years-old-today|url-status=live}}</ref><ref>{{cite web|url=https://247wallst.com/special-report/2021/09/16/cost-of-a-computer-every-year-since-1970/|title=Cost of a Computer Every Year Since 1970|last=Comen|first=Evan|work=24/7 Wall St.|date=September 16, 2021|access-date=November 19, 2021|archive-date=November 19, 2021|archive-url=https://web.archive.org/web/20211119014803/https://247wallst.com/special-report/2021/09/16/cost-of-a-computer-every-year-since-1970/|url-status=live}}</ref><ref>{{cite book|url=https://books.google.com/books?id=6u16DAAAQBAJ&pg=PA139|title=Introduction to the History of Computing: A Computing History Primer|last=O'Regan|first=Gerard|series=Undergraduate Topics in Computer Science |publisher=[[Springer Science+Business Media]]|date=2016|access-date=November 19, 2021|page=139|doi=10.1007/978-3-319-33138-6|isbn=978-3-319-331386|s2cid=24592919 }}</ref> that Commodore sold as many as six million units worldwide. However, Commodore UK refuted that figure and said that the entire Amiga line sold between four and five million computers.<ref name="IM-OG">{{cite book|url=https://books.google.com/books?id=G6saEAAAQBAJ&pg=PT57|title=Impossible Mission I & II - The Official Guide|last=Weßling|first=Holger|publisher=Acorn Books|date=2020|access-date=November 19, 2021|page=57|isbn=9781789824575}}</ref> Indeed, ''[[Ars Technica]]'' provides a year-by-year graph of the sales of all Amiga computers.<ref>{{cite web|url=https://arstechnica.com/gaming/2017/01/a-history-of-the-amiga-part-10-the-downfall-of-commodore/|title=A history of the Amiga, part 10: The downfall of Commodore|last=Reimer|first=Jeremy|work=[[Ars Technica]]|date=January 22, 2017|access-date=November 19, 2021|archive-date=August 10, 2022|archive-url=https://web.archive.org/web/20220810034527/https://arstechnica.com/gaming/2017/01/a-history-of-the-amiga-part-10-the-downfall-of-commodore/|url-status=live}}</ref>

The machine is reported to have sold 1,160,500 units in Germany (including Amiga 500 Plus sales).<ref>{{Cite web |last=Bergseth |first=M. |date=November 25, 2014 |title=AMIGA SOLD IN UNITS BY COMMODORE IN GERMANY REVEALED |url=https://distrita.com/amiga-sold-in-units-by-commodore-in-germany-revealed/ |website=Distrita - Where to Go |access-date=May 15, 2023 |archive-date=July 13, 2017 |archive-url=https://web.archive.org/web/20170713160208/https://distrita.com/amiga-sold-in-units-by-commodore-in-germany-revealed/ |url-status=bot: unknown }}</ref>

== Amiga 500 Plus ==
{{Infobox computer
| image = Amiga 500 Plus (white background).jpg
| caption = Base of the Amiga 500 Plus, with the Italian variant of the keyboard
| name = Commodore Amiga 500 Plus
| developer = [[Commodore International]]
| family = [[Amiga]]
| type = [[Home computer]]
| release date = {{Start date and age|1991}} (UK)
| discontinued = 1992
| os = [[AmigaOS]] v2.04
| media = 880 [[kilobyte|KB]] floppy disks
| cpu = [[Motorola 68000]] @ {{nowrap|7.16 MHz ([[NTSC]])}}<br> {{nowrap|7.09 MHz ([[PAL]])}}
| memory = 1 [[megabyte|MB]] (10 [[megabyte|MB]] maximum)
| display = 640×256, 4 [[Color depth|bpp]] @ {{nowrap|50 [[Frame rate|Hz]] ([[PAL]])}}<br> 640×200, 4 [[Color depth|bpp]] @ {{nowrap|60 [[Frame rate|Hz]] ([[NTSC]])}}
| sound = 4× 8-bit channels PCM at max. {{nowrap|28 [[kHz]]}} with 6-bit volume in stereo
| predecessor = Amiga 500
| successor = [[Amiga 600]]
}}

The '''Amiga 500 Plus''' (often '''A500 Plus''' or simply '''A500+''') is a revised version of the original Amiga 500 computer. The A500+ featured minor changes to the motherboard to make it cheaper to produce than the original A500. It was notable for introducing new versions of [[Kickstart (Amiga)|Kickstart]] and [[AmigaOS|Workbench]], and for some minor improvements in the custom chips, known as the [[Enhanced Chip Set]] (or ECS).

Although officially introduced in 1992, some Amiga 500 units sold in late 1991 actually featured the revised motherboard used in the A500+. Although the Amiga 500+ was an improvement to the Amiga 500, it was minor. It was discontinued and replaced by the [[Amiga 600]] in summer 1992, making it the shortest-lived Amiga model.{{cn|date=February 2025}}

=== Compatibility problems ===
{{Unreferenced section|date=March 2021}}
Due to the new Kickstart v2.04, quite a few popular games (such as ''[[Treasure Island Dizzy]]'', ''[[Lotus Esprit Turbo Challenge]]'', and ''[[SWIV]]'') failed to work on the Amiga 500+, and some people took them back to dealers demanding an original [[Kickstart_(Amiga)|Kickstart]] 1.3 Amiga 500. This problem was largely solved by third parties who produced Kickstart [[Read-only memory|ROM]] switching boards, that could allow the Amiga 500+ to be downgraded to Kickstart 1.2 or 1.3. It also encouraged game developers to use better programming habits, which was important since Commodore already had plans for the introduction of the next-generation [[Amiga 1200]] computer. A program, Relokick, was also released (and included with an issue of [[CU Amiga]]) which loaded a [[Kickstart (Amiga)|Kickstart]] 1.3 [[ROM]] image into memory and booted the machine into Kickstart 1.3, allowing most incompatible software to run (the software did take up 512&nbsp;KB of system memory, meaning that some 1&nbsp;MB only games would now  fail for lack of available memory). In some cases, updated compatible versions of games were later released, such as budget versions of [[Lotus (video game series)|Lotus 1]] and [[SWIV]], and an update to ''[[Bubble Bobble]]''. [[Double Dragon 2]] by Binary Design received an update for [[Amiga Enhanced Chip Set|ECS]] machines with the "Amiga phase-alternated linescan version 4.01/ECS". This solved compatibility issues with the graphics which appeared garbled on ECS machines, and it also slashed the in-game loading times from around 20 seconds to just over 6.

=== Technical specifications ===
* [[Motorola 68000]] [[central processing unit|CPU]] running at {{nowrap|7.09 MHz}} (PAL) / {{nowrap|7.16 MHz}} (NTSC), like its predecessor
* 1 MB of [[Chip RAM]] (very early versions came with 512&nbsp;[[Kibibyte|KB]]<ref>{{Cite web |title=Amiga Beginners Series #2 - Amiga Models |url=https://www.amigaretro.com/index.php?page=5 |access-date=2024-07-13 |website=www.amigaretro.com |archive-date=July 13, 2024 |archive-url=https://web.archive.org/web/20240713163205/https://www.amigaretro.com/index.php?page=5 |url-status=live }}</ref>)
* Kickstart 2.04 (v37.175)
* Workbench 37.67 (release 2.04)
* Built-in battery backed RTC (Real Time Clock)
* Full [[Enhanced Chip Set|ECS]] chipset including new version of the [[MOS Technology Agnus|Agnus]] chip and [[Original Amiga chipset#Denise|Denise]] chip

== See also ==
{{Portal|Amiga}}
* [[List of Amiga models and variants]]
* [[Minimig]]{{snd}}an [[open-source hardware]] [[field-programmable gate array|FPGA]] implementation

==Notes==
{{Notelist}}

== References ==
{{Reflist}}

== Further reading ==
* {{cite book|ref={{harvid|Introduction to the Amiga 500|1987}}|url=https://archive.org/details/Introduction_To_The_Amiga_500_v1.3.2_1987_Commodore_315839-15|title=Introduction To The Amiga 500|publisher=[[Commodore International]]|date=1987|access-date=November 24, 2021}}
* {{cite book|url=https://archive.org/details/amiga-hardware-reference-manual-3rd-edition|title=Amiga Hardware Reference Manual|edition=Third|last1=Greenley|first1=Larry|last2=Green|first2=Mark|last3=Baker|first3=Dan|publisher=[[Addison-Wesley]]|date=August 1991|access-date=November 24, 2021|isbn=0-201-56776-8}}
* {{cite book|ref={{harvid|Technical Reference Manual|1987}}|url=https://archive.org/details/Commodore_Amiga_A500_A2000_Technical_Reference_Manual_1987_Commodore|title=Commodore Amiga A500/A2000 Technical Reference Manual|publisher=[[Commodore International]]|date=1987|access-date=November 25, 2021}}
* {{cite book|ref={{harvid|ROM Kernel Reference Manual|1990}}|url=https://archive.org/details/amiga-rom-kernal-reference-manual-libraries-and-devices|title=Amiga ROM Kernal Reference Manual: Libraries And Devices|edition=2nd|author=[[Commodore International]]|publisher=[[Addison-Wesley]]|date=June 1990|access-date=November 25, 2021|isbn=0-201-18187-8}}
* {{cite book|url=https://books.google.com/books?id=Gr74DwAAQBAJ|title=The Future Was Here: The Commodore Amiga|last=Maher|first=Jimmy|publisher=[[MIT Press]]|date=2018|access-date=November 19, 2021|doi=10.7551/mitpress/9022.001.0001|isbn=9780262535694}}

==External links==
{{Commons category|Amiga 500}}
* [https://www.retro32.com/buyers-guide/21012020126-commodore-amiga-500-buyers-guide Amiga 500 Buyers guide]

{{Amiga hardware}}
{{Commodore International}}
{{Authority control}}

[[Category:Amiga]]
[[Category:Computer-related introductions in 1987]]
[[Category:68000-based home computers]]