Changes
/* ZX Spectrum +3 */
[[File:ZX Spectrum Plus3.jpeg|thumb|ZX Spectrum +3]]
The '''ZX Spectrum +3''' looked similar to the +2 but featured a built-in 3-inch [[floppy disk]] drive (like the Amstrad CPC 6128) instead of the tape drive, and was in a black case. It was launched in 1987, initially retailed for £249<ref>{{Cite journal| last = South | first = Phil | year = 1987 | month = July | title = It's here... the Spectrum +3 | journal = [[Your Sinclair]] | issue = 17|pages = 22–23 | url = http://www.worldofspectrum.org/showmag.cgi?mag=YourSinclair/Issue19/Pages/YourSinclair1900022.jpg | accessdate =5 August 2008 }}</ref> and then later £199<ref>{{Cite journal| author = Amstrad | year = 1987 | month = November | title = The new Sinclair has one big disk advantage | journal = [[Sinclair User]] | issue = 68 | pages = 2–3 | url = http://www.worldofspectrum.org/showmag.cgi?mag=SinclairUser/Issue068/Pages/SinclairUser06800002.jpg | accessdate =5 August 2008 | authorlink = Amstrad }}</ref> and was the only Spectrum capable of running the [[CP/M]] operating system without additional hardware.
The +3 saw the addition of two more 16 kB ROMs. One was home to the second part of the reorganised 128 ROM and the other hosted the +3's disk operating system. This was a modified version of Amstrad's [[PCWDOS]] (the disk access code used in [[LocoScript]]), called +3DOS. These two new 16 kB ROMs and the original two 16 kB ROMs were now physically implemented together as two 32 kB chips. To be able to run CP/M, which requires RAM at the bottom of the address space, the bank-switching was further improved, allowing the ROM to be paged out for another 16 kB of RAM.
* move 1 byte address in ROM
Some older 48K and a few older 128K games were incompatible with the machine. The ZX Interface 1 was incompatible due to differences in ROM and expansion connector; therefore it was not possible to connect and use the Microdrive units.<ref>{{Cite journal| last = Goodwin | first = Simon | year = 1987 | month = December | title = Tech Tips - +3 Faults | journal = [[Crash (magazine)|Crash]] | issue = 48 |pages = 145 | accessdate = 20 August 2012 }}</ref>
The ZX Spectrum +3 power supply provides the same voltages as the one supplied with +2A/B. This power supply has the same DIN connector so can also be used with the +2A/B. However, the power supply purchased with the +3 had "Sinclair +3" written on the case.<ref>{{cite web|url=http://www.yorkdistribution.co.uk/acatalog/York_Distribution_Power_supply_for_Spectrum_128___2A___3_2337.html|title=Power supply for Spectrum 128, +2A, +3|publisher=York Distribution Limited|accessdate=21 December 2012}}</ref> Production of the +3 ceased in December 1990, believed to be in response for Amstrad relaunching their CPC range. At the time, it was estimated about 15% of ZX Spectrums sold had been +3 models. Production of the +2B (the only other model then still in production) continued, as it was believed not to be in competition with other computers in Amstrad's product range.<ref>{{Cite journal| year = 1990 | month = December | title = Death of the +3 | journal = [[Your Sinclair]] | issue = 60|pages = 10–11 }}</ref> It was eventually discontinued in 1992.<ref name="bbc6572711"/>
Production of the +3 ceased in December 1990, believed to be in response for Amstrad relaunching their CPC range. At the time, it was estimated about 15% of ZX Spectrums sold had been +3 models. Production of the +2B (the only other model then still in production) continued, as it was believed not to be in competition with other computers in Amstrad's product range.
=== ZX Spectrum +2B and +3B ===
