Looking at early microcomputers, all of them have support for something resembling ASCII, occasionally a few letters with accents and things were included also. And occasionally another alphabet such as Russian or Armenian was squeezed in.
But the Arabic alphabet is a bit more complicated. It's written (mostly) right-to-left, and as far as I can tell it needs many diacritics to be legible. What was the first computer to support this alphabet?
Computers with user-definable graphics, like the ZX Spectrum or the TI-99/4a, qualify if you can show a software title which uses them to render a sequence of bytes as Arabic text. I am not only considering the Arabic language here but any language which can be written with Arabic letters (eg. Urdu, Turkmen etc.)