[Coco] FPGA VS Software Emulators

Bill Nobel b_nobel at hotmail.com
Tue Jul 25 13:42:56 EDT 2017

Close Dave, the DE0 version uses external SRAM chips @ 10ns.  The CocoFPGA does also, but use a much higher speed chip set for the SRAM.

Bill Nobel
b_nobel at hotmail.com<mailto:b_nobel at hotmail.com>

On Jul 25, 2017, at 11:39 AM, Dave Philipsen <dave at davebiz.com<mailto:dave at davebiz.com>> wrote:

Actually I believe that the CoCo3FPGA uses SRAM @ 10ns access time. I'm not 100% sure on this but I believe the CoCo on a chip is based upon the DE0 Nano which does not have SRAM but uses SDRAM instead.


On 7/25/2017 8:50 AM, Bill Nobel wrote:
Hi Walter good points to bring up.

The Coco on a chip project uses SRAM @ 10ns access time. The CocoFPGA uses a faster SRAM which is why the speed difference.  The reason software emulators can do a lot better speed is just that. Its a Software emulation, no speed limitations as it is a software clock that is changeable based on the CPU it’s being run on.  FPGA’s still have to communicate to real hardware which will pass a limitation to the speeds they run, depending on what is being interfaced. Each hardware device will have a different speed rating.  Both FPGA projects run on an internal clock of 50mhz which is then divided down to to a speed for each device connected (whether it’s internally programmed or physically attached).

There are many other factors that affect speeds as well, but in this case the FPGA is not really the limitation, it’s the hardware that attaches to it.

Bill Nobel
b_nobel at hotmail.com<mailto:b_nobel at hotmail.com><mailto:b_nobel at hotmail.com>

On Jul 25, 2017, at 1:02 AM, Walter Zambotti <zambotti at iinet.net.au<mailto:zambotti at iinet.net.au><mailto:zambotti at iinet.net.au>> wrote:

Before I start this is not a one is better than the other debate.

This is about better understanding each technology.

Ok so my initial thoughts regarding FPGA (as I really know nothing) were
hardware simulation should
provide an end product that is more efficient and faster than a general
CPU/software emulator.

However this does not appear to be the case.

The CoCo on a chip project emulates an 8mhz CoCo.

The CoCoFPGA project a 25mhz CoCo.

And VCC on my i5 (3.3 ghz) a 133mhz CoCo.

What causes these differences in end speed?

Why are the two FPGA projects so different in speed?

Why are both FPGA solutions slower than a CPU/software solution?

Is it the particular FPGA hardware itself?

Would high end FPGAs provide a different result?

I've just download the FPGA for Dummies eBook from Altera so I'm starting my
education process.


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