Re: A new boot code for Alex Freed's Pseudodisk ][...

["Michael J. Mahon" <mjmahon@aol.com>]

Alex Freed wrote:
> Deckard wrote:
> > > The big problem with my design is that you can't swap the simulated
> > > floppy on-the-fly.
> >
> > I don't like to switch off/switch on my computer each time I want to
> > boot a new image.
> > Why don't you add an entry point in the rom code with something like
> > that:
>
> Let's think together about it. The ROM is huge, but only 256 bytes are
> mapped in at a time. When the unit operates in floppy emulation nibble 
> mode, the visible ROM page is a copy of the real floppy controller's 
> ROM. It doesn't have much space for extra code, but suppose we can 
> somehow map in another ROM page - say with a physical switch. How do we 
> make the 6502 jump to this code? If a program needs to be run for that, 
> why does it need a ROM entry point and not talk to the AVR directly?

How about typing PR#6 then holding a button while pressing RETURN.  The
button would map in a "selector" page that would set a switch to keep
the page mapped until it was time to return to the disk ROM.

-michael

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