[Rpcemu] Thoughts on RPCemu development

Ed Avis eda at waniasset.com
Mon Sep 3 12:02:04 BST 2007


>>There was the G8 from State Machine or 
>>something like that, a more upmarket rival to the ColourCard, which 
>>required special software to use the whole megabyte of VRAM. 
>>It does appear that 480K is a hard limit.
>
>I've just had a look at the ModeExtension service (having just 
>coded a module for 800x600x256), and I think there's a way 
>around this for an emulator. You can change the screen address 
>used by the VDU drivers,

Is this another couple of parameters in the big hairy structure you have to create to define your new video mode?

>I suspect what the G8 did was map video RAM in podule space 
>(16k at a time) and the special software paged this around as 
>VDU calls required.

According to <http://acorn.chriswhy.co.uk/docs/StateMachine/G8_User_Guide.pdf> the 'G8 Professional' card had a megabyte of VRAM but could not use it in the RISC OS desktop.  So I suspect they weren't bothering to trick or redirect VDU calls but had their own graphics API (for which no software was ever written).

-- 
Ed Avis <eda at waniasset.com> 

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