Re: Hardware emulation of 6509 using 6502?

From: Mia Magnusson <mia_at_plea.se>
Date: Mon, 5 Mar 2018 21:38:03 +0100
Message-ID: <20180305213803.00003411@plea.se>
Den Fri, 02 Mar 2018 22:43:58 +0100 skrev Michał Pleban
<lists@michau.name>:
> smf wrote:
> 
> > You need to be able to disconnect the 6502 data lines from the bus,
> > or you'll wipe out the vic2 data.
> 
> Hm, you are correct. So far we focused on the 610, where AEC is not
> connected. But in the P500 there must be a possibility to tri-state
> the data bus.

Are you sure AEC is used in the P500?

According to the 4256041 schematics (found at Zimmers site, from the
Funet archives) the AEC isn't used. There are a separate set of buffers
(244, 245) around the 64k dram in page 0.

Are there any known versions of P500 which differs from this?

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Received on 2018-03-05 22:04:59

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