Re: Difference between R65C02 and original 6502 (wrt 6509 emulation)

From: Jim Brain <*brain_at_jbrain.com*> Date: Wed, 17 Apr 2019 20:45:30 -0500 Message-ID: <0e8ec59b-e16c-ecf0-4f9b-bf4ffc901b58_at_jbrain.com> · brain_at_jbrain.com

On 4/17/2019 6:06 AM, Michał Pleban wrote:
> Mia Magnusson wrote:
>
>> What I'm trying to say is that if the registers at 0 and 1 are hidden
>> from read, but listens to writes, in '816 mode, everything should work
>> fine as the code that switches back from '816 mode to 6509 emulation
>> could just write the 0/1 registers at $F0000/$F0001 as there is no risk
>> of corrupting memory for the 8088 board. With those registers written
>> it's then safe to switch back from '816 mode to 6509 emulation mode and
>> the registers will contain the correct values even if previous code had
>> written to $x0000/$x0001.
> I suppose if we go the route to switch to the '816 mode to write to
> memory, then switch back to the 6502 mode to call the KERNAL, then it
> should probably be quite easy for the IPC code to make sure that the CPU
> is found in correct bank when it is switched back to the 6502 mode?
>
> Regards,
> Michau.
>
>
>
>
>
So, hide the registers in '816 mode?

JIm


-- 
Jim Brain
brain_at_jbrain.com
www.jbrain.com