Re: Hardware emulation of 6509 using 6502?

On 02/03/2018 10:16, Mia Magnusson wrote:

> Which one, $E or $F? And why? 

Assuming the 6509 in the p500 works the same as the 6510 in the c64, 
then you can use the vic2 fetches to write to ram underneath $0/$1

http://codebase64.org/doku.php?id=base:ram_beneath_00_and_01

If so, it would be possible to write code for the p500 that would put 
vic2 in 0-3fff of either of the ram banks and use the $3fff mechanism to 
write to $0/$1. It would work on real hardware, but not on your replacement.

The only way to emulate this behaviour is to disconnect the databus and 
let it float, which requires new hardware.



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