+3, not +3A. I suspect you're thinking of the Amstrad Spectrum +2 (grey, largely the same as the Sinclair ZX Spectrum 128) vs Amstrad Spectrum +2A (black, cont

+3, not +3A. I suspect you're thinking of the Amstrad Spectrum +2 (grey, largely the same as the Sinclair ZX Spectrum 128) vs Amstrad Spectrum +2A (black, contained a +3 motherboard minus the FDD controller, and less compatible with external peripherals).