RE: [cc65] Atari Extended Memory Driver Anybody?

From: Shawn Jefferson <sjefferson1shaw.ca>
Date: 2012-08-12 06:28:37
> From: owner-cc65@musoftware.de [mailto:owner-cc65@musoftware.de] On Behalf
> Of Oliver Schmidt

<snip>

> - Have a 256 byte "soft window" inside the driver like the Apple driver:
> .bss
> window:		.res	256		; Memory "window"
> 
> - Dynamically create a short asm routine on the cpu stack. The address
> of the "soft window" and the address in the extended memory are
> written as constants into the routine.

I've implemented this idea and have some working code for everything except
copyfrom/copyto right now.

> - Implement copyfrom/copyto by creating a new asm routine on the stack
> for every 256 bytes to copy. The routine is similar to the one above
> but instead of using the "soft window" it is using the current final
> source/target address. For the last bytes left probably less than 256
> call the routine with X != 0.

I still have to implement this, but I suspect I'll use this advice almost
exactly as you've described it.

However, I've never built a loadable driver... or used them in any way. I'll
have to look into doing that to see if it works completely as a loadable
driver.

After this is done, I can use the same framework for a RAM under the OS
driver, among others:

- SpartaDOS aware driver that can check with RAM banks are available for use
for instance
- RAMBO
- VBXE RAM driver



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Received on Sun Aug 12 07:06:24 2012

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