Re: Hardware emulation of 6509 using 6502?

From: Michał Pleban <*lists_at_michau.name*> Date: Sun, 25 Feb 2018 22:58:25 +0100 Message-ID: <5A933181.4080102@michau.name> · lists_at_michau.name

Hello!

Jim Brain wrote:

> The incoming PHI0IN of the 6502 needs to be shifted "forward" by 17nS. 
> That's tougher than just shifting it back.  I am going to look at PHI1
> inverted and see if I can use that to signal the start of the cycle.

Yes, I guess I meant "back" in the sense you meant "forward". Anyway, I
don't think it's any harder in either direction.

Create a 5-bit 32 MHz counter, which is reset by falling edge of PHI2
incoming from motherboard.

Then output 0 if the counter has value 31 or 0-14, 1 otherwise (if you
wanted to shift in other direction, you would output 0 for values 1-16).

Regards,
Michau.

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