[Coco] What would a CoCo successor have to have as a minimum?

John Kent jekent at optusnet.com.au
Sat Nov 20 22:49:43 EST 2010

I might also add that the software emulator has to perform memory 
decoding, bounds checking and memory mapping all sequentially. It also 
has to emulate the hardware, which is presumably on an an I/O space 
access, but may also be concurrent with the CPU execution. The FPGA does 
this all in parallel. So even if there are say 100 CPU cycles to one 
FPGA clock cycle there is a lot the CPU has to do in those 100 cycles.

On 21/11/2010 2:05 AM, John Kent wrote:
> FPGAs are much slower than you average PC with clock speeds around 
> 100MHz as opposed to 2 or 3 GHz, however, The FPGA can be incrementing 
> the Program Counter of the 6809 at the same time as it's performing 
> some ALU function or calculating a register offset.  Also the PC has 
> to execute multi-cycle instructions to interpret the 6809 instruction, 
> (albeit piplelined) so even with the most optimized assembler code, 
> you are talking about many cycles and many instructions to do what the 
> FPGA does in one cycle.


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