> Under sufficiently heavy CPU load, the mouse pointer became slightly
> less responsive. There's no reason for that to happen if it's all
> implemented in hardware.

On the Acorn there was no concept of CPU load as we have today - the CPU 
was always running at 100%. The OS just gave control to each running 
program in turn, when it had done all of them it started again. It was 
up to each program to give control back to the OS when it was done. If 
you didn't you got to use 100% CPU, which is what most full-screen games 
did and the default for simple programs.

IIRC the mouse pointer was updated by interrupt, so unless you 
deliberately disabled interrupts or wrote some buggy interrupt handler 
you never got any issue with pointer responsiveness.

> Clearly the graphics is being redrawn from scratch rather than being
> recopied from an off-screen buffer. That a piece of software doesn't
> take advantage of a feature doesn't mean the feature doesn't exist. It
> seems to me that the attitude of modern software is "hey, why bother
> optimising it? Just make the user buy more hardware."

Or rather, "it works fine on my 1 month old uber developer PC with 
nothing else running so i won't bother optimising it to work on a 5 year 
old pc".

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