[Coco] MC6809 Inards

[jdaggett at gate.net]

Mike

I did  not follow every reference patent, but if one did then one maybe led to 
those patents. I did not specific search on the PDP-11. 

The MC6800 and offspring use an incrementer linked with the PCR and a 16 bit 
temp register. There is a paent that does describe how to do precharge from a 
carry. Looks as if this does the actual increment/decrement by one or by two. 

james

On 4 Oct 2006 at 12:50, KnudsenMJ at aol.com wrote:


> 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.

>