Re: CBM2 v9958 Hires-Color Graphics Card

From: fhw72 <webmaster_at_frank-wolf.org>
Date: Mon, 4 Feb 2019 03:01:10 -0600 (CST)
Message-ID: <1549270870086-0.post@n4.nabble.com>
Segher Boessenkool wrote
> On Fri, Feb 01, 2019 at 02:12:39AM -0600, vossi wrote:
>> At page A-6 3.4 are the absolute,x addressing cycles.
>> There is also a T3 cycle (always - not only at page boundarys) with 
>> discarded read. But I measured this with my 6509 and had no dummy read!!!
> 
> Interesting.  It sounds like the 6509 does away with the last cycle of 
> those insns (which handles the carry in the address, on 6502).
> 
> Segher

Very interesting: I've taken a *brief* look at the decode rom of the 6509R7
and the 6502D and found no apparent change...

As soon as time permits I will dig into this deeper!
However can someone confirm this changed behaviour independently?

In case someone wants to take a look:

6509R7A_decode.jpg
<http://cbm-hackers.2304266.n4.nabble.com/file/t374877/6509R7A_decode.jpg>  



--
Sent from: http://cbm-hackers.2304266.n4.nabble.com/
Received on 2019-02-04 11:00:03

Archive generated by hypermail 2.2.0.