Changes

==Amstrad models== === ZX Spectrum +2 ===

The '''ZX Spectrum +2''' was [[File:Amstrad]]'s first Spectrum 128-2.png, coming shortly after their [[Sinclair Research Ltd#Amstrad acquisition|thumb|ZX purchase of the Spectrum +2Arange and "Sinclair" brand]]in 1986. The machine featured an all-new grey case featuring a spring-loaded keyboard, dual joystick ports, and a built-in cassette recorder dubbed the "Datacorder" (like the [[File:Amstrad CPC 464]]), but was in most respects identical to the ZX Spectrum Plus3128.jpegThe main menu screen lacked the Spectrum 128's "Tape Test" option, and the ROM was altered to account for a new 1986 Amstrad copyright message. These changes resulted in minor incompatibility problems with software that accessed ROM routines at certain addresses. Production costs had been reduced and the retail price dropped to £139–£149.<ref>{{Cite journal| last = Phillips | first = Max | year = 1986 |thumbmonth = November|title = ZX Spectrum +32|journal = [[Your Sinclair]]| issue = 11 | page = 47 | url = http://www.ysrnry.co.uk/articles/spectrumplustworeview.htm | accessdate =29 August 2006}}</ref>

The new keyboard did not include the BASIC keyword markings that were found on earlier Spectrums, except for the keywords ''LOAD'', ''CODE'' and ''RUN'' which were useful for loading software. This was not a major issue however, as the +2 boasted a menu system, almost identical to the ZX Spectrum 128, where one could switch between 48k BASIC programming with the keywords, and 128k BASIC programming in which all words (keywords and otherwise) must be typed out in full (although the keywords are still stored internally as one character each). Despite these changes, the layout remained identical to that of the 128.<ref>{{Cite journal| last =Goodwin | first =Simon | year =ZX Spectrum +21987 | month = December | title = Tech Tips - Amstrology | journal = [[Crash (magazine)|Crash]] | issue =48|pages =143 | accessdate =20 August 2012 }}</ref>

"Amstrad sPeCCy4128 The ZX Spectrum +2 power supply was a grey"version of the ZX Spectrum+ and 128 power supply.<ref>{{cite web|url=http://www.dataserve-retro.co.uk/contents/en-uk/d8.html|title=Spectrum +2, +2A, and +2B Spares|author=DataServe Retro|accessdate=19 August 2012}}</ref>{{clear}}

=== ZX Spectrum +2A ===[[File:Spectrum 128-2.png|thumb|ZX Spectrum +2A]]The '''ZX Spectrum +22A''' was Amstrad's first a variant of the Spectrum, coming shortly after their purchase +3 housed a black version of the Spectrum range and "Sinclair" brand in 1986+2 case mouldings. The machine featured an all-new grey case featuring a spring-loaded keyboard, dual joystick ports, and a built-in cassette recorder dubbed the "Datacorder" Spectrum +2A/+3 motherboard (like AMSTRAD part number Z70830) was designed such that it could be assembled without the [[CPC_old_generation | Amstrad CPC 464floppy disk controller]])or associated logic and a +2 style "datacorder" connected.<ref>''Spectrum +3 Service Manual''. AMSTRAD. p.18.</ref> Originally, but was in most respects identical Amstrad planned to introduce an additional disk interface for the +2A/+2B called the '''AMSTRAD SI-1''',<ref>Spital, Ivor. ''Sinclair ZX Spectrum 128+2A''. The main menu screen lacked AMSTRAD, 1987. p.354.</ref> however this never appeared. If an external disk drive was added, the Spectrum 128's "Tape Test+2A" option, and on the ROM was altered system OS menu would change to account for a new 1986 Amstrad copyright message. These changes resulted in minor incompatibility problems with software that accessed ROM routines at certain addresses. Production costs had been reduced and the retail price dropped to £139–£149+3.

The new keyboard did not include power supply of the BASIC keyword markings that were found on earlier Spectrums, except for ZX Spectrum +2A used the keywords ''LOAD'', ''CODE'' and ''RUN'' which were useful for loading software. This was not a major issue however, same [[pinout]] as the +2 boasted a menu system3. However, almost identical to the ZX Spectrum 128, where one could switch between 48k BASIC programming power supply purchased with the keywords, and 128k BASIC programming in which all words (keywords and otherwise) must be typed out in full (although +2A/B had "Sinclair +2" written on the keywords are still stored internally as one character each)case. Despite these changes, the layout remained identical to that of the 128<ref>{{cite web|url=http://hardware.speccy.org/hardware/Fuente+2A/imagenes/vista_superior.jpg|title=Image of Spectrum +2A power supply|accessdate=21 December 2012}}</ref>{{clear}}

===ZX Spectrum +2A3 ===

"Amstrad sPeCCy4128 black"[[File:ZX Spectrum Plus3.jpeg|thumb|ZX Spectrum +3]]The '''ZX Spectrum +2A3''' was produced looked similar to homogenise the +2 but featured a built-in 3-inch [[floppy disk]] drive (like the Amstrad's range 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... Although the case reads "ZX Spectrum +2", the +2A3 | journal = [[Your Sinclair]] | issue = 17|pages = 22–23 | url = http:/B is easily distinguishable from the original +2 as the case /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 restored to the standard only Spectrum blackcapable of running the [[CP/M]] operating system without additional hardware.

The +2A was derived from Amstrad's +3 4.1 ROM model, using a new motherboard which vastly reduced the chip count, integrating many of them into a new ASIC. The +2A replaced the +3's disk drive and associated hardware with a tape drive, as in the original +2. Originally, Amstrad planned to introduce an additional disk interface, but this never appeared. If an external disk drive was added, the "+2A" on the system OS menu would change to a +3. As with the ZX Spectrum +3, some older 48K, and a few older 128K, games were incompatible with the machine. ===ZX Spectrum +2B===The '''ZX Spectrum +2B''' signified a manufacturing move from Hong Kong to Taiwan later in 1987. ===ZX Spectrum +3=== "Amstrad sPeCCy6128" 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 and then later £199 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 &nbsp;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 AMSDOS[[PCWDOS]] (the disk access code used in [[LocoScript]]), called +3DOS. These two new 16 &nbsp;kB ROMs and the original two 16 &nbsp;kB ROMs were now physically implemented together as two 32 &nbsp;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 &nbsp;kB of RAM.

* Reading a non-existent I/O port no longer returned the last attribute; caused some games such as ''[[Arkanoid]]'' to be unplayable

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 wasn't 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"/>  === ZX Spectrum +2B and +3B === The ''ZX Spectrum +2B'' and ''ZX Spectrum +3B'' were functionally similar in design to the Spectrum +2A and +3.<ref>''Spectrum +2B/+3B Service Manual''. AMSTRAD.</ref> The main electronic differences being simply changes to the generation of the audio output signal to resolve problems with [[Clipping (audio)|clipping]] and the removal of the external tape loading input ("ear" pin).

Production of Unlike the +3 ceased in December 1990. Although still accounting for one third of all home computer sales in 2A the UK at the time, production of the model was ceased by Spectrum +2B motherboard (AMSTRAD part number Z70833) does not have provision for floppy disk controller circuitry so cannot be assembled as a +3B. The +3B motherboard is Amstrad at that pointpart number Z70835.