[Coco] (very very slightly OT) 6800 emulator

[jdaggett at gate.net]

Again I reitterate that the emulation board was a functional equivalent of the 6809 
that was built around the 6800.  Also to do a beadboard where you implement the 
6809 hardware in logic would be emensely complex and time consuming to get 
running. 

Chances are the instruction set and register movement were not at the full 2 MHz 
speed rated for the final silicon. Also when you go from evalu ation/breadboard to 
actual silicon timings do change. Back in the 70's it was not uncommon to do 
multiple passes on the silicon. In fact if the first silicon worked at any speed 
above 10KHz that was a blessing. Usually by the third pass you had pretty much 
production ready ICs.  Only a minor tweak in the fourth pass would meet the final 
design goals. 

Today an IC as complex as the 6809 can be done is one or two passes of silicon. 
Six to nine months as compared to two years. 


james 


On 30 Apr 2007 at 0:17, Joel Ewy wrote:

> It does if you want to emulate it at full speed or better.  But
> Motorola's purpose in emulating the 6809 on the 6800 wasn't to play
> cool CoCo games from the past, er, from the future.  It was to test
> the instruction set, and maybe to begin writing 6809 software (maybe
> assemblers and such) before there were actual 6809 chips available.
> Yes, it would have been slower than the 6809, but it could have been
> made to work just the 6809 would have.