It looks like
this model, with an ARM 2 processor at 4/8 Mhz.
The Acorns were really popular over here in schools, but never really made it as a home computer. They ran RiscOS, which was built into the ROM and had a few interesting features (ie a taskbar before Win95, which IMO worked better). The graphics were average, but couldn't match Amiga (no copper, blitter etc). AFAIK the last OS was released a few years back, and Acorn is owned by someone else. I think they were still selling h/w then as well, but is was very custom (and extremely expensive).
---edit---
RiscOS was dam nasty.
But it's nastiness paled in comparison to what windoze was at the time :-o Perhaps I'm biased as they were probably the second computers I ever used (1st was Amiga of course :-D ) but they always seemed OK.
