[kiwijamo]

Earlier models (such as the A3000 my family bought in the early '90s) booted from ROM and would drop you at a desktop in literally 1-2 seconds. The POST screen was basically just "RISC OS 2.00 2048K RAM" (or something along those lines) and then all of a sudden it shows the desktop ready to use. Sadly later models would boot from HDD instead (copying the approach used by Microsoft for Windows) and these took ages to boot.

[mattbee]

They still booted to a desktop from ROM, but the hard disc boot sequence had to update lots of kernel modules that had since been updated. Acorn would roll those updates back into the next version of the RISC OS ROMs, and (for some computers) you could buy newer ROMs. But the boot sequence generally took longer as time went on (though still only 10-15s from my memory).