"BTX Decoder Modul II", the one in REU-like case, has the 6803 MPU and is interfaced to the "main CPU" with the 68HC34 dual port RAM. Regards, Konrad 2018-05-23 14:35 GMT+02:00 Steve Gray <sjgray@rogers.com>: > Very cool! FYI, the Commodore 64 BTX cartridges also contain a 6809, but i > haven't seen schematics for them anywhere. They also have their own video > chip. Other than that, there's really not much info out there about them. > > Steve > > > ________________________________ > From: Jim Brain <brain@jbrain.com> > To: cbm-hackers@musoftware.de > Sent: Wednesday, May 23, 2018 2:09 AM > Subject: 6809 in a C64 > > Ruud: > In reference to this old posting: > http://www.softwolves.com/arkiv/cbm-hackers/13/13116.html > I thought I'd note that I designed a C64 cartridge containing a MC6809 and > some RAM. I know it's not exactly the same as your idea, but it is easier > to prototype. > https://www.facebook.com/go4retro/photos/a.386509271508869.1073741826.386509238175539/984731561686634/?type=3&theater > The initial goal is to multiplex the two CPUs, allowing the 6809 to access > some shared RAM on the low PHI2 portion of the cycle, and 64 access on the > high portion. Then, I'll try to speed up the 6809 to 4MHz and see if I can > keep the shared memory in place. > Possibly later, I'll see if I can have the 6809 take over the bus like > SuperCPU and Chameleon64, but I suspect I have to learn quite a bit more > about the system bus. > Jim > > -- > Jim Brain > brain@jbrain.com > www.jbrain.com > > >Received on 2018-05-23 16:00:29
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