Editing ZX Spectrum (section)

=== ZX Spectrum 16K/48K ===
[[file:ZXSpectrum48k.jpg|thumb|ZX Spectrum 16K/48K (Dimensions (mm): 233×144×30 (W×H×D) @ ≈552 grams).<ref name = HCHOF>{{cite web | url = http://www.gondolin.org.uk/hchof/hchof.php | title = The Home Computers Hall of Fame, The Machines | last = Stratford | first = Christopher | date = 11 May 2014 | website = gondolin.org.uk | archive-url = https://web.archive.org/web/20150317112736/http://gondolin.org.uk/hchof/hchof.php | archive-date = 17 March 2015 | url-status = live | access-date = 31 March 2015 }}</ref>]]

The original ZX Spectrum is remembered for its rubber [[chiclet keyboard]], diminutive size and distinctive rainbow motif. It was originally released on 23 April 1982 with 16&nbsp;KB of RAM for {{inflation|UK|125|1982|fmt=eq|cursign=£|orig=yes}} or with 48&nbsp;KB for {{inflation|UK|175|1982|fmt=eq|cursign=£|orig=yes}};<ref name="High Street Spectrum">{{Cite journal |date= February 1983 |title= The High Street Spectrum |journal= ZX Computing |page= [https://archive.org/details/ZX-computing-1983-02/page/n42 43] |url= https://archive.org/details/ZX-computing-1983-02 |access-date= 27 April 2016 |url-status= live |archive-url= https://web.archive.org/web/20170316134253/https://archive.org/details/ZX-computing-1983-02 |archive-date= 16 March 2017 }}<!-- This cannot be fixed via Wayback archive due to robots.txt preventing archiving of the site. --></ref> these prices were reduced to {{inflation|UK|99|1983|fmt=eq|cursign=£|orig=yes}} and {{inflation|UK|129|1983|fmt=eq|cursign=£|orig=yes}} respectively in 1983.{{sfn|Gilbert|1983a|p=13}} Owners of the 16&nbsp;KB model could purchase an internal 32&nbsp;KB RAM upgrade, which for early "Issue 1" machines consisted of a [[daughterboard]]. Later issue machines required the fitting of 8 [[dynamic random-access memory|dynamic RAM]] chips and a few [[transistor-transistor logic|TTL]] chips. Users could mail their 16K Spectrums to Sinclair to be upgraded to 48&nbsp;KB versions. Later revisions contained 64&nbsp;KB of memory but were configured such that only 48&nbsp;KB were usable.<ref name = ys-64k-1984-09>{{Cite journal | last = Goodwin | first = Simon | date = September 1984 | title = Suddenly, it's the 64K Spectrum! | journal = [[Your Spectrum]] | issue = 7 | pages = 33–34 | url = http://www.users.globalnet.co.uk/~jg27paw4/yr07/yr07_33.htm | archive-url = https://web.archive.org/web/20140522194918/http://www.users.globalnet.co.uk/~jg27paw4/yr07/yr07_33.htm | archive-date = 22 May 2014 | url-status = live | access-date = 31 March 2015 | quote = So the first three issues of the Spectrum used a combination of eight 16K chips and eight 32K ones. The latest machines depart from that combination, but Sinclair Research has been very quiet about the alteration. }}</ref> External 32&nbsp;KB RAM packs that mounted in the rear expansion slot were available from third parties. Both machines had 16&nbsp;KB of onboard ROM.{{sfn|Leigh|2018|p=68}}

An "Issue 1" ZX Spectrum can be distinguished from Issue 2 or 3 models by the colour of the keys – light grey for Issue 1, blue-grey for later machines.<ref name = ps-s48kv-2003-09>{{cite web | url = http://www.nvg.ntnu.no/sinclair/computers/zxspectrum/spec48versions.htm | work = Planet Sinclair | title = Spectrum 48K Versions | last = Owen | first = Chris | archive-url = https://web.archive.org/web/20150321023603/http://rk.nvg.ntnu.no/sinclair/computers/zxspectrum/spec48versions.htm | date = 6 September 2003 | archive-date = 21 March 2015 | url-status = live | access-date = 31 March 2015 | quote = It is often possible to determine which version of the Spectrum 16/48K one has without opening the case, as there are a number of clues... }}</ref> Although the official service manual states that approximately 26,000 of these original boards were manufactured,<ref name="Servicing">{{cite book |last1=Thorn (EMI) Datatech Ltd|title=Servicing Manual For ZX Spectrum |date=March 1984 |publisher=Sinclair Research Ltd |page=4.3 |url=https://k1.spdns.de/Vintage/Sinclair/82/Sinclair%20ZX%20Spectrum/Repair/ZX%20Spectrum%20Service%20Manual%20(OCRed).pdf |access-date=31 January 2019 |archive-url=https://web.archive.org/web/20190201013410/https://k1.spdns.de/Vintage/Sinclair/82/Sinclair%20ZX%20Spectrum/Repair/ZX%20Spectrum%20Service%20Manual%20%28OCRed%29.pdf |archive-date=1 February 2019 |url-status=live }}</ref> subsequent serial number analysis shows that only 16,000 were produced, almost all of which fell in the serial number range 001-000001 to 001-016000.<ref>{{Cite web|title=ZX Spectrum Models|url=https://spectrumforeveryone.com/technical/zx-spectrum-models/|access-date=9 September 2021|website=Spectrum for Everyone|language=en-GB|archive-date=9 September 2021|archive-url=https://web.archive.org/web/20210909125915/https://spectrumforeveryone.com/technical/zx-spectrum-models/|url-status=live}}</ref> An online tool now exists to allow users to ascertain the likely issue number of their ZX Spectrum by inputting the serial number.<ref>{{Cite web|title=Spectrum For Everyone Serial DB|url=https://serials.spectrumforeveryone.com/|access-date=9 September 2021|website=Spectrum For Everyone Serial DB|language=en|archive-date=9 September 2021|archive-url=https://web.archive.org/web/20210909125915/https://serials.spectrumforeveryone.com/|url-status=live}}</ref>

These models experienced numerous changes to its motherboard design throughout its life; mainly to improve manufacturing efficiencies, but also to correct bugs from previous boards. Another issue was with the Spectrum's power supply. In March 1983, Sinclair issued an urgent recall warning for all owners of models bought after 1 January 1983.{{sfn|Popular Computing Weekly|1983b|p=6}} Plugs with a non-textured surface were at risk of causing shock, and were asked to be sent back to a warehouse in [[Cambridgeshire]] which would supply a replacement within 48 hours.{{sfn|Popular Computing Weekly|1983b|p=6}}{{sfn|Backhurst|1983a|p=5}}