Re: Microcontroller "PEEKing" into C64 memory?

On Thursday 21 January 2016, 11:18:22 Leif Bloomquist <leif@schemafactor.com> 
wrote:
> Hi all,
> 
> I have an idea for a project that would require an external
> microcontroller to be able to "peek" into parts of the C64 Memory.
> 
> It wouldn't matter where.  I/O1 and I/O2 might be easiest, but some
> unused space like $02A7-$02FF could also work and not interfere with
> external devices.   Only would need 8 bytes or so.
> 
> What would be the easiest way to go about this?
> 
> I'm not an electrical guy at all, but my initial concept would be a
> dual-port SRAM along with a decoder (74LS138, etc) that signals when
> the particular address range is selected (as well as on Write). Then
> have the data lines and a few of the address lines connected to the
> SRAM that gets written to when that triggers. From there the
> microcontroller can read the SRAM from the other port and do its
> thing.
> 
> Would this be easiest, or are there other better ways?
> 
> There's also this, a cool project (but total overkill), proves it can
> be done:  http://hackaday.com/2014/12/26/dual-porting-a-c64-flash-cart/
> 
> (Plan B would be to to have a UART and go serially through the User
> Port, but then special software would be needed on the 64, more
> involved than just a POKE.)

what exactly is the goal? "Only would need 8 bytes or so" sounds like what you 
want is more like mapping in some "registers"? (and in that case, some 
properly decoded locations in I/O space would be my choice)


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