Sinclair ZX Spectrum (Sinclair BASIC) had subroutines and looping. See: https://worldofspectrum.org/ZXBasicManual/zxmanchap4.html https://worldofspectrum.org/Z

Sinclair ZX Spectrum (Sinclair BASIC) had subroutines and looping. See: https://worldofspectrum.org/ZXBasicManual/zxmanchap4.html https://worldofspectrum.org/ZXBasicManual/zxmanchap4.html https://worldofspectrum.org/ZXBasicManual/zxmanchap5.html https://worldofspectrum.org/ZXBasicManual/zxmanchap5.html Timex Basic featured on the "clones" they produced is said to be a a superset of Sinclair basic, in which case then Timex Basic has the same features. I am not 100% when it comes to the ZX81. I did most of my programming on the ZX Spectrum. I wrote a database engine and front end on it. (There really was no backend and frontend it was all just one program. But the engine was versatile and easy to build a new front end on top of. I tried selling it for a while without luck. (Which was probably a good thing). Looking back on it now its embarrassing. I had no real idea what a database was, or how to functioned inside. But given my age and tools available it was ok-