Re: Hardware emulation of 6509 using 6502?

From: Jim Brain <>
Date: Thu, 19 Jul 2018 21:47:42 -0500
Message-ID: <>
On 7/19/2018 3:17 PM, Mia Magnusson wrote:
> Well, phi1 and phi2 being swapped in the data sheet were discovered
> this year, so ;)
> The question is which devices do depend on this?
Ruud will have to answer.
> There is already an 18MHz clock on the B motherboards, so except for
> the P, it's easy to obtain a synchronized clock with higher frequency.
> In fact, using an adapter on top of the timing shift register gives 9
> states throughout the 2MHz cycle of the CPU clock, and by using both
> flanks of the 18MHz clock you can get 18 steps within each 2MHz period
> cycle.
> Of course it would be more cumbersome for a user to have to solder a
> wire or add some clip-on-thing, but using this in a hypothetical future
> B replacement/replica motherboard would be trivial.
Yes, but the likelihood that someone will use it goes up markedly the 
fewer things they have to jumper or solder.


Jim Brain
Received on 2018-07-20 05:00:05

Archive generated by hypermail 2.2.0.