Re: Hardware emulation of 6509 using 6502?

From: Jim Brain <brain_at_jbrain.com>
Date: Sun, 8 Jul 2018 01:03:14 -0500
Message-ID: <943ab38e-43cd-68ed-6d66-f27aa05f5d0d@jbrain.com>
On 7/7/2018 3:56 PM, Michał Pleban wrote:
> 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.
Yep, and I see it, but it might be that the CPU does not.
>
> 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.
Not sure the old board has any value.

I am awaiting a WDC 65C02S to test.  If that does not shed light, I'll 
solder up a second one of the new unit, test it here and send one.

Do you have a Xilinx XPLD/FPGA programmer?

Jim

>
> Regards,
> Michau.
>

-- 
Jim Brain
brain@jbrain.com
www.jbrain.com
Received on 2018-07-08 09:00:04

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