[Coco] 6x09 instruction timings

[jdaggett at gate.net]

On 20 Jan 2007 at 17:01, Joel Ewy wrote:


> Ok, stupid question.

> 

> I know that the Q clock and the E clock are 180 degrees out of phase,

> and that the CPU uses this relationship to separately clock different

> internal states.  But when reading instruction set timings, a cycle is

> one complete cycle of the E clock, without respect to what Q is doing

> (though their period is the same), is that correct?  So at 1.78 MHz, 1

> cycle of the E clock is a little more than .56 microseconds, if I

> understand this correctly.

> 

***********
In the MC6809/HD6309 the E clock period is the determination for cycle time. At High speed 
the Coco's have a cycle time of 579 nanoSec. The Q clock is phased shifted by 90degrees 
and leads the E clock by that phase. The Q clock is used internally to gate sychronous 
operation fo the internal logic for the MC6809 and probably for gating some ot the 
microcode states within the HD6309.  

james

> Just looking at Sockmaster's Hicolor code and thinking about how much

> processing could be done during the scan lines, vertical blanking,

> etc.

> 

> JCE

> 

> 

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