[Coco] MC6809 Inards

[KnudsenMJ at aol.com]

In a message dated 10/4/06 12:12:45 PM Eastern Daylight Time,  
jdaggett at gate.net writes:

>From  that era many chips were breadboarded before anyone laid out the 
design 
on  silicon. According to Terry Ritter, the MC6809 was first done on a 
breadboard  
using LS-TTL logic. Judging from the MC6801 patents, that is very  doable.  



In searching patents on the 6809, did you find any references to the DEC  
PDP-11 mini?
 
That machine introduced a ton of patentable features,, including the  
universal bus, program-counter-relative addressing, auto-increment/decrement  
addressing, and the Overflow Bit.
All found in our beloved 6809 and not many other CPUs of its day.
--Mike K.