Re: Hardware emulation of 6509 using 6502?

From: Michał Pleban <*lists_at_michau.name*> Date: Sat, 07 Jul 2018 22:56:05 +0200 Message-ID: <5B4128E5.7000207@michau.name> · lists_at_michau.name

Jim Brain wrote:

> Yes, and no.  It is easier to set up the 8 port PC-based LA, so I added
> code in the CPLD to activate a pin when the address was reached, and
> then traced it and the port values and a signal indicating whether the
> port was showing the $0 or $1 value.  I see that sometimes, the port
> changes to #$1 a number of times, and then it shows your address.  The
> number of tests varies.

There SHOULD be $01 appearing, because KERNAL starts testing the RAM in
the first bank. We should analyze closely the last time that it appears,
because it is the offending instruction.

I have an Intronix 34 logic analyzer which can make traces with very
high resolution. If you sent me the two boards, I could make detailed
traces of what's happening.

Regards,
Michau.