RE: Hardware emulation of 6509 using 6502?

From: Baltissen, GJPAA (Ruud) <ruud.baltissen_at_apg.nl>
Date: Tue, 17 Jul 2018 06:31:15 +0000
Message-ID: <54F350D2C6501448A3EE14B7854C5FB57A5613FC@WSV10441N3.office01.internalcorp.net>
Hallo Jim,


> The system uses the E pin on the '816 to interpret setting the port pins:
> ....

I really like that :) That would give me the 65816 I always liked to have. It does mean that the Kernal has to be rewritten but I wouldn't mind.

May I politely point you to something? In the early days I equipped a VIC-20 with a 65816 and an ISA expansion. After building the whole thing I found out that I had misunderstood the behavior of the RDY input. Negating RDY does stop the 65816 from performing any instruction but does NOT stop it from outputting the content of the bank register on to the data bus when E is (L).

In time I found a solution by keeping the clock input (H) during the time RDY was (L). You'll find the schematic at:

  http://baltissen.org/newhtm/65sc816.htm


I hope this is some help.


Met vriendelijke groet / With kind regards, Ruud Baltissen

www.Baltissen.org




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Received on 2018-07-17 09:00:17

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