Z80 @ 3.5 Mhz - 32KB ROM - 128K RAM

The ever evolving home computer industry of the time saw developments from lots of other computer manufacturers. The Atari ST & Commodore Amiga, both produced by the US, were both 16-bit machines with potentially more power, compared to the 8-bit Sinclair Spectrum. Thankfully Sir Clive released the latest member of the Spectrum stable, the "128." 

Priced at just under £180, The new Spectrum's memory was given a much needed increase from 48K to 128K, which also formed the basis for the new name. This memory, to retain compatibility, was "paged" however. This meant that areas of memory had to swapped with the "active" area of memory before they could be used. Realistically this meant that all of the memory was not available to a programmer in one go, but had to be used in chunks. Of course this made the previous multi-load games able to load into the Spectrum's memory in one hit. No more did you get the messages "STOP TAPE" and "START TAPE" right in the middle of your game. Looks-wise, the computer was very similar to the Spectrum+ , which was based on Sinclair's answer to the business market, the QL. The machine was slightly longer however, due to an enlarged heat-sink inside, but otherwise looked like another member of the Sinclair family. All of the biggest changes were inside the case.

For the first time, the ZX Spectrum was able to output it's sound via the speakers on the TV it was connected to, rather than a very basic beeper inside the computer's case, which was how all Spectrums had worked previously. And on top of this the sound was given a much needed power injection, with a 3 channel chip capable of producing the most realistic sounds heard yet from a Spectrum. The infamous "Dot Crawl" problem was fixed on the Spectrum for the first time also. This fix addressed the problem of colours "bleeding" into each other at their boundaries, and creating almost a moving pattern on the screen. Other than this, the graphics remained unaltered which was probably for compatibility reasons. A section of user-programmable graphics, however, had two new commands "PLAY" & "SPECTRUM" shoe-horned into the space. This meant that some, older, programs that used these two spaces would have the two keywords visible on screen, in 128K mode, rather than the graphics they intended. Swapping to 48K mode would solve the problem.

There were also changes with the addition of a MIDI (Musical Instrument Digital Interface) controller built into the motherboard, although there were no physical MIDI ports on the machine itself to control keyboards and the like. There was also an "RGB" port, used for connection to a monitor, although again proprietary.

Even though the micro was ready for shipping in 1985, due to considerable stocks still of the Spectrum+, Sinclair Research decided to hold off until January of 1986 before the public saw the 128 hit the shelves. 

This was really the beginning of the end for the Spectrum. The 16-bit computers were making a big impact with consumers with the 8-bit machines thought of as inferior in comparison at the time. During 1986, Sinclair Research sold the rights to the ZX Spectrum to Amstrad. As well as all stock held at the factory, the deal also included the Sinclair & Spectrum names, when used with a computer. Sinclair Research did produce another computer however, although under the company name "Cambridge Computer" - the Z88 in 1987. After this the company decided to focus on other projects.

Image sources: Public Domain