Medium 640x512, 8KB
Small 400x320, 9KB
Medium 640x512, 10KB
Small 400x320, 29KB
Small 191x90, 1932bytes
After ArthurOS came RISC OS 2, the first proper multitasking OS for the Archimedes range. RISC OS traditionally comes in ROM form, so that's four chips to unsocket and change. Gone is the rather horrendous orange/blue colour scheme, to be replaced with a more sedate grey theme; the desktop palette was eight shades of grey followed by a range of eight colours, a fairly decent spread although purples and magentas are hard to reproduce even with dithering. 256 (fixed) colour desktops were also possible, with 64 colours in four shades, but window furniture and filer icons had to fit in with the 16 colour palette (256 colour filer icons tended to look corrupted in 16 colour desktops as the filer display routine didn't take the current mode into account until RISC OS 3).
RISC OS 2 introduced some staples that are still with us today; unlike ArthurOS you could add new programs to the iconbar along the bottom (a feature that Windows was to replicate badly years later), and some of the example images on this page include a red circle which is a program being developed for a book. To keep track of all of these programs and generally manage resources such as the size of the RAM disc the Task Manager was introduced, represented here as an "A" icon, the Archimedes logo. This would later be replaced by Acorn's own logo in RISC OS 3. Most programs just displayed their memory usage and could be killed from here as well as through the program itself; with some programs, and especially the resources sections, you just dragged the bars to the required level. So for instance, the RAM disc was created by dragging the corresponding bar from 0K to, say, 160K; if that wasn't right, so long as the disc was empty, you could resize it to your hearts content. Later third party hacks allowed it to resize while full, or even auto-resize as needed.
The palette utility allowed you to change to numbered modes - 12 was a 16 colour low resolution mode, 15 was the same in 256 colours, and so on. You could also change the desktop palette to any 16 from 4096, and I think the greyscales were linked so changing the first or eighth colour would interpolate the other six "greys" for a nice spread. This has all been changed so that you just choose colours and resolutions and the correct mode is worked out, and the palette editor has gone (which is why I wrote my own palette utilities)