[cc65] Banking out ROM (was: TGI preview)

From: Fatih AygŁn <cyco1301yahoo.com>
Date: 2009-11-14 12:19:34

Ullrich von Bassewitz wrote:
> The Plus/4 runs with all ROMs banked out. [...] I hoped to get a similar

> setup for the C128 before the 2.13 release, but dropped it because of lack of
> time.

How do those platforms handle disk i/o?

I now have a working setup for Atari XL/XE. (It's not extensively tested, and I'm not sure 
if serial input ready irq can handle the extra overhead in all circumstances on the real 
hardware, it must be served very quickly, especially with high speed devices). But in Atari, 
you have all of the ROM banked in or out all at once. So I can't load anything into the extra
memory from disk, because the i/o routines are in the rom and when the rom is enabled to
call them, they just try to write over the rom, which obviously doesn't work.

Shawn Jefferson wrote:
> Does the built-in config still have the start of RAM at $2E00 ?  You
can get away with $2000 
> for most DOSes in wide-spread use.  The extra
RAM was for any drivers (like the 850) that 
> might be loaded low (from
what I recall.)  I always change it to $2000 myself.

Yes, it's still $2E00. Sometimes I even go with $0600 :) Some emulators have a dos in the rom 
and others have virtual hard disks. On the real hardware, I have an sio2pc program and a virtual 
dos (I call it PseuDos) that just forwards the requests to the PC in the shortest possible time and
allows me to load as low as $800 :)

I know MyDos 4.5 allows as low as $1F00. Do you know what's the lower limit for Dos 2.0s and 
Dos 2.5?

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Received on Sat Nov 14 12:19:43 2009

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