Re: ROM Dump of Amiga Keyboard controller

From: Kajtár Zsolt <>
Date: Tue, 24 Jun 2014 23:14:42 +0100
Message-ID: <>
Hash: SHA1

>>> Guys, I have a bunch of the 1520 ploter MCUs... They are 6500/1 of 
>>> course.
>> It would be interesting to have the ROM dumped... I've created a 1520 
>> emulation for VICE, but I never could exhaustively test all incorrect 
>> input to it. So while the emulation seems ok for correct input, for 
>> buggy programs it may certainly work differently. With a disassembly 
>> this could be improved.
> It was one of the main reasons I started the discussion on this matter 
> some two years ago. The KBD controller is just another reason. I am
> still willing to do the experiment, provided there is a well-backed
> consensus on how this should be done.

Just like two years ago I'm still on the opinion that the easiest would be
to wire it into an existing 6502 based system where the external processor
is doing the fetches for the 6500/1 so that port PC would be directly
connected to the external data bus.

Synchronization could be ensured by using half the clock of the 6500/1 for
the external processor, and starting them parallel using the reset signal.
If the phases don't match there are only a few variations to try.

After releasing the test mode the external processor could handle the
communication with the 6500/1 side by using the other ports and some IO
interface chip.

But whatever. No one really cared two years ago, so this must be

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