Hardware-based vs software-based emulation

On Fri, Feb 17, 2017 at 08:47:12AM +0000, smf wrote:
>On 16/02/2017 10:54, silverdr@wfmh.org.pl wrote:
>>Well, yeah.. but that's not the same as the original thing, is it?
>
>No, but it would take some pressure off the price of the originals & 
>it might mean that there is some software worth running.

The Commodore 65 is essentially emulating the Commodore 64 in hardware.  
(OK, it is also a valuable collector's item.) The Mega65 is emulating 
the Commodore 65 and other 8-bit systems in FPGA hardware, similar to 
the C-One (and theoretically its sibling C64DTV too).

I hope this will not escalate into a flame war, but I am curious:

What is the benefit of implementing the emulation of a full system in 
VHDL or FPGA, instead of implementing it in software?

The only reason to use hardware-based emulation that I can think of is 
the ability to connect original (or compatible) peripherals.

With software-based emulation, you can use free (as in freedom) software 
tools, while with FPGAs you typically are limited to the closed-source 
tools and formats provided by the chip manufacturer.

If you do not need the connectivity to authentic peripherals that cannot 
be emulated with simple GPIO, wouldn't it be better to use 
software-based emulation either on commodity hardware or on 
hobbyist-friendly hardware such as the Dragonbox Pyra, built around a 
reasonably open system-on-chip? Or wouldn't it be better to develop a 
Mega65-style mainboard but implement the emulation in software, ditching 
the "non-trivial" peripheral ports, keeping only joystick ports and the 
serial bus? Instead of analog video and audio you would typically get 
HDMI output that works nicely with modern displays (but admittedly, not 
at all with an authentic CRT).

The recently released NES Classic is just an ARM SoC running an 
emulator. Nintendo has a long history of releasing old titles bundled 
with an emulator.

Speaking of authentic peripherals, I wonder if there would be any demand 
for Atari/Commodore joystick cables or joysticks. I learned some years 
ago that my joystick cords have become unreliable, and I would prefer to 
replace the cords with ones that have a molded plastic connector.  
(Personally I do not need new joysticks, only new cords; the TAC-2 are 
virtually indestructable.) If there is interest in this, I could ask a 
friend who has good contacts to various manufacturers in China. Maybe a 
small batch could be done for a reasonable price.

	Marko

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