A couple of years after Amstrad bought Sinclair and released their first Spectrum – the Grey +2 (Z70500) with an integrated datasette, the time came for another model with an integrated disk drive – the Spectrum +3 (Z70830), which although based on the look of the Grey+2, was a heavily re-designed system, comprising much of the components including the ULA into an ASIC chip. As part of the cost-cutting Amstrad have also re-designed the grey tapedeck Spectrum model creating a new Spectrum – Black +2A which has the design and the technology of Spectrum +3, but with a built-in tapedeck instead of a disk drive.
First units of the Black +2A were direct copies of Spectrum +3 – they were made using the same motherboard (Z70830), hence the “Internal Disk Drive” slot, even though the model has a built-in tapedeck. Not many can be found nowadays as they are thought to have been released mainly for the Spanish market, since the UK market was still getting through the Grey +2 models.
A sample of Fantasy World Dizzy music on Z70830:
Later, in an effort to bring the production costs lower still, the Z70830 motherboard (used in Spectrums +3 and +2A) has been further redesigned. A shorter version without the unnecessary disk drive expansion slot has been created (Z70833) – only for use in black Spectrums +2 with a datasette.
A sample of Fantasy World Dizzy music on Z70833:
The production of Z70833 has continued for the rest of the lifespan of the Black Spectrums +2s. Although there have been subtle changes made between revisions in an effort to lower the production costs, including the changes to factories making them, the main board remained the same.
There are 3 revisions of the Z70833 motherboards known in existence. The first 2 issues were made in a factory in Taiwan, then in order to lower manufacturing cost even more the production has been moved to a factory in China where the final issue 4 (the most cut-cost version) was made, which is where the Spectrums with “+2B” on the back of the case come from.