Editing ZX Spectrum (section)

=== ZX Spectrum 128 {{anchor|spectrum128}}===
[[file:ZX Spectrum128K.jpg|thumb|ZX Spectrum 128]]

In 1985, Sinclair developed the ZX Spectrum 128 (codenamed ''Derby'') in conjunction with their Spanish distributor Investrónica (a subsidiary of [[El Corte Inglés]] department store group).{{sfn|Frey|1985|p=5}}{{sfn|Bourne|1985b|p=5}}{{sfn|Frey|1986|p=11}} Investrónica had helped adapt the ZX Spectrum+ to the Spanish market after their government introduced a special tax on all computers with 64&nbsp;KB RAM or less,<ref>{{in lang|es}} Ministerio de Economía y Hacienda (BOE 211 de 3 September 1985), [http://www.boe.es/buscar/doc.php?id=BOE-A-1985-18847 Real Decreto 1558/1985, de 28 de agosto, por el que se aclara el alcance del mínimo específico introducido en la subpartida 84.53.B.II del Arancel de Aduanas, por el Real Decreto 1215/1985] {{webarchive|url=https://web.archive.org/web/20130430111506/http://www.boe.es/buscar/doc.php?id=BOE-A-1985-18847 |date=30 April 2013 }}. Rango: Real Decreto, Páginas: 27743 – 27744, Referencia: 1985/18847.</ref> and a law which obliged all computers sold in Spain to support the Spanish alphabet and show messages in Spanish.<ref name="BOE">{{in lang|es}} Ministerio de Industria y Energía (BOE 179 de 27 July 1985), [http://www.boe.es/buscar/doc.php?id=BOE-A-1985-15611 Real Decreto 1250/1985, de 19 de junio, por el que se establece la sujeción a especificaciones técnicas de los terminales de pantalla con teclado, periféricos para entrada y representación de información en equipo de proceso de datos] {{webarchive|url=https://web.archive.org/web/20130430104621/http://www.boe.es/buscar/doc.php?id=BOE-A-1985-15611 |date=30 April 2013 }}. Rango: Real Decreto, <!--pages, or pp. here? --> Páginas: 23840–23841, Referencia: 1985/15611.</ref>

The appearance of the ZX Spectrum 128 is similar to the ZX Spectrum+, with the addition of a large external [[heat sink|heatsink]] for the internal 7805 [[voltage regulator]] to the right-hand end of the case, replacing the internal heatsink in previous versions. This external [[Heat sink|heatsink]] led to the system's nickname, "The [[Toast rack|Toast Rack]]".<ref>{{cite web|url=http://retrorevivalshop.co.uk/index.php?main_page=product_info&cPath=7&products_id=60|title=Murata 5v Switching Regulator (for Toastrack models)|website=Retro Revival Shop|access-date=13 November 2021|archive-date=13 November 2021|archive-url=https://web.archive.org/web/20211113115246/http://retrorevivalshop.co.uk/index.php?main_page=product_info&cPath=7&products_id=60|url-status=live}}</ref> New features included 128&nbsp;KB RAM with RAM disc commands, three-channel audio via the [[General Instrument AY-3-8910|AY-3-8912]] chip, [[MIDI]] compatibility, an [[RS-232]] serial port, an [[RGB]] monitor port, 32&nbsp;KB of ROM including an improved BASIC editor, and an external keypad.{{sfn|Wilkins|2015a|p=17}}

The machine was simultaneously unveiled for the first time and launched in September 1985 at the [[SIMO TCI|SIMO '85]] trade show in Spain, with a price of 44,250 [[Spanish peseta|pesetas]]. Sinclair later presented the ZX Spectrum 128 at [[The May Fair Hotel]]'s Crystal Rooms in London, where he acknowledged that entertainment was the most common use of home computers. Due to the large number of unsold Spectrum+ models, Sinclair decided not to start it selling in the United Kingdom until January 1986 at a price of £179.<ref name="sincuser-49">{{Cite journal|date=April 1985 |title=<!-- wrong title this is quote: -->Clive discovers games – at last |journal=[[Sinclair User]] |issue=49 |page=53 |url=http://www.sincuser.f9.co.uk/049/128lnch.htm |url-status=dead |archive-url=https://web.archive.org/web/20060924093908/http://www.sincuser.f9.co.uk/049/128lnch.htm |archive-date=24 September 2006 }}</ref><ref name=nerd/>

The [[Zilog Z80]] processor used in the Spectrum has a [[16-bit computing|16-bit]] address bus, which means only 64&nbsp;KB of memory can be directly addressed. To facilitate the extra 80&nbsp;KB of RAM the designers used [[bank switching]] so the new memory would be available as eight pages of 16&nbsp;KB at the top of the address space. The same technique was used to page between the new 16&nbsp;KB editor ROM and the original 16&nbsp;KB BASIC ROM at the bottom of the address space.<ref name="128+3-Manual-8">{{cite web|url=http://www.worldofspectrum.org/ZXSpectrum128+3Manual/chapter8pt24.html|title=Spectrum 128+3 Manual, Chapter 8 Part 24|publisher=Amstrad|access-date=20 August 2012|url-status=live|archive-url=https://web.archive.org/web/20120615075843/http://www.worldofspectrum.org/ZXSpectrum128+3Manual/chapter8pt24.html|archive-date=15 June 2012}}</ref>

The new sound chip and [[MIDI]] out abilities were exposed to the BASIC programming language with the command <code>PLAY</code> and a new command <code>SPECTRUM</code> was added to switch the machine into 48K mode, keeping the current BASIC program intact (although there is no command to switch back to 128K mode). To enable BASIC programmers to access the additional memory, a RAM disk was created where files could be stored in the additional 80&nbsp;KB of RAM. The new commands took the place of two existing user-defined-character spaces causing compatibility problems with certain BASIC programs.<ref name="128+3-Manual-7">{{cite web|url=http://www.worldofspectrum.org/ZXSpectrum128+3Manual/chapter7.html|title=Spectrum 128+3 Manual, Chapter 7|publisher=Amstrad|access-date=20 August 2012|url-status=live|archive-url=https://web.archive.org/web/20120615074428/http://www.worldofspectrum.org/ZXSpectrum128+3Manual/chapter7.html|archive-date=15 June 2012}}</ref> Unlike its predecessors, it has no internal speaker, and can only produce sound from a television speaker.<ref name="128-Manual-9">{{cite web|url=http://www.worldofspectrum.org/ZXSpectrum128Manual/sp128p09.html|title=World of Spectrum – Documentation – ZX Spectrum 128 Manual Page 9|access-date=28 April 2016|url-status=live|archive-url=https://web.archive.org/web/20160424174241/http://www.worldofspectrum.org/ZXSpectrum128Manual/sp128p09.html|archive-date=24 April 2016}}</ref>