The ZX81 was resolutely black-and-white, like its predecessor the ZX80. Its flat keyboard was unaffected by drinks spilled on it and it came with 1k RAM as standard. You could get a plug-in 16k RAM module that went in the back of it. It was no feckin' use at all.
Colour didn't really come about properly until the ZX Spectrum, Commodore VIC-20 and C64. Also the ORIC-1, plus contemporary BBC Model B and Acorn Electron. There, I'm showin' me age now, so I am.