[Coco] MC6809 Inards

[jdaggett at gate.net]

Steve

I have looked for all patents since 1976 that would have been assigned to Tandy 
or Radio Shack and have found nothing. That means the GIME chip had nothing 
that was patentable or that the assignee is under a different company or an 
individual. 


Right now I have concentrated on the MC6809 and finding all related patents. It 
has been interesting reseach. 

james


On 3 Oct 2006 at 20:49, Steve Ostrom wrote:

> Any chance that patents could be reviewed for the hidden graphics modes 
> for the Coco3?
> 
> -- Steve --
> 
> 
> jdaggett at gate.net wrote:
> 
> >All
> >
> >My what you can find out when you start reading patents. I was searching the US patent 
> >records for anything that might be related to the MC6809 and actually found about four or 
> >five patents that could be directly related to the processor. There is no one single patent that 
> >is, in whole, a complete description of the processor. Instead there are several patents when 
> >combined, give insight to the internal workings of the microprocessor. I even found several 
> >patents regarding the MC6820/21 PIA chip. 
> >
> >Some interesting things that I have found:
> >
> >1) The MC6809 and the MC6801/3 are probably more closer related internally than the 
> >MC6809 is to the MC6800. An interesting thing is the main CPU processor core schematic 
> >for the MC6801 is included in patent # 4266270, Microprocessor having dual internal data 
> >busses. Beware this is a huge schematic if you want to print it out. It prints out to about 28 
> >letter size pages. 
> >
> >2) It appears that there are three internal clocks in the MC6809/01/03 and maybe even the 
> >MC6811/HC11.The clock system in the MC6801 patent (4266270) has three clocks. I have 
> >verified that t here are indeed three clocks running through the schematic. 
> >
> >3) the address bus internally is split into two separate busses, A0 -A7 and A8 to A15. Also 
> >As the title to patent 4266270 suggests there are two seaprate 8 bit data busses in the 
> >MC6801/3 processor. When I pulled patent 4200912 and looked at the figures #1 and #2 my 
> >eyes nearly popped out of my sockets. Here it was nearly indentical to the MC6809. Low 
> >and behold t his patent depicts a MC6809 like processor with two internal 8 bit data busses 
> >that has a switch to make the two a single 8 bit buss. The main scope of patent 4200912 
> >was a processor having multile IRQ processors. The embodied processor has the IRQ and 
> >FIRQ inputs. The registers include the USP,  Y pointer register, and the Direct Page 
> >Register. Plus a few others. 
> >
> >I have started writing a blurb on this and hope to put it up on my webpage soon. This was 
> >neat stuff and by pouring through about ten to 15 patents,I came away with a greater 
> >understanding of what thought processes went through during the design of the MC6809. 
> >Also a greater  understanding of several of Motorola's processors and how they function 
> >internally. One t hing that I do understand better is how fast the processor can be clocked. 
> >Best I could figure is about 6 MHz and that is pushingit real hard. Three MHz is most likely 
> >the max for most parts. To many levels of logic gates to ripple through to get much faster. 
> >
> >more later
> >
> >james 
> >
> >   
> >
> >  
> >
> 
> 
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