used the same pinout as the +3 and has "Sinclair +2" written on the case. ZX Spectrum +2B and +3B The ZX Spectrum +2B and ZX Spectrum +3B were functionally similar in design to the Spectrum +2A and +3. The main electronic differences were changes to the generation of the audio output signal to resolve problems with clipping. Unlike the +2A and +3, the Spectrum +2B and +3B do not share a common motherboard. The +2B board (AMSTRAD part number Z70833) has no provision for floppy disk controller circuitry and the +3B motherboard (Amstrad part number Z70835) has no provision for connecting an internal tape drive. Production of all Amstrad Spectrum models ended in 1992. Clones and re-creations Official clones Sinclair licensed the Spectrum design to Timex Corporation in the United States, that sold several machines under the Timex Sinclair brand. An enhanced version of the original Spectrum, with better sound, graphics and other modifications was marketed in the US by Timex as the Timex Sinclair 2068. Timex's derivatives were largely incompatible with Sinclair systems. Some of the Timex innovations were later adopted by Sinclair Research. A case in point was the abortive Pandora portable Spectrum, whose ULA had the high resolution video mode pioneered in the T/S 2068. Pandora had a flat-screen monitor and Microdrives and was intended to be Sinclair's business portable. After Amstrad bought the computer business of Sinclair Research, Sir Clive retained the rights to the Pandora project, and it evolved into the Cambridge Computer Z88, launched in 1987. Starting in 1984, Timex of Portugal developed and produced several Timex branded computers, including the Timex Computer 2048, highly compatible with the Sinclair ZX Spectrum 48K, which was very successful in both Portugal and Poland. An NTSC version was also made, initially intended for a United States release, but it was sold only in Chile, Ecuador and Argentina. Timex of Portugal also made a PAL version of the T/S 2068, called the Timex Computer 2068 (or TC 2068 for short) which had different buffers for both the ULA and the CPU, which significantly increased the compatibility with ZX Spectrum software when compared to the North American model (the T/S 2068). The expansion port was also modified and made to be 100% compatible with the ZX Spectrum's, which bypassed the need for a "Twister Board" expansion that the T/S 2068 needed to make it compatible with ZX Spectrum