[Coco] MC6809 Inards
jdaggett at gate.net
jdaggett at gate.net
Wed Oct 4 14:31:28 EDT 2006
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.
>
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