6502.org

Just released this 6502 Atari 2600 emulator with a BASIC compiler for the Commodore 64:
http://relationalframework.com/GameLoad ... _BASIC.htm

I agree that you're technically right (after I once saw a post from Garth explaining the difference): just as an 8P8C modular connector is not an RJ45 jack, and a Podium is not a Lectern.

However, I would suggest that, except in the most technical of literature, its probably not a hill worth dying on. Society as a whole has decided that they are called Emulators and nit-picking in our tiny corner of the internet won't change that.

Indeed, if Mr SQL called it a simulator then other people interested in what they (rightly or wrongly) call an emulator will never find it because they're not looking for a simulator, they're looking for an emulator.

(No, not even technically right, just a difference of dialect.)

It's an emulator, it runs these Atari ROM's with pixel perfect cycle precise emulation.

The VM emulates the TIA presenting a shadow register bus to the Atari 2600 program which runs unchanged just as if it were talking on the bus to a real TIA.

(I think you're unlikely to convince - the main thing is not to be put off by negative commentary. Almost everyone running a 6502 system these days will use "emulation" the way that you and I do. I think only those few who learnt their trade in the 70s or before are likely to have the other sense in mind. And even they know exactly what is meant!)

(It is a pity that the forum continues to see these negative pedantic points made - they make the place unwelcoming, and yet most of us are actually pleased when new people join up.)

Had a gander at your website, and I'm confused.

Is this a program that can be used natively on a real C64, or is it some kind of extension module for that the VICE C64 emulator?

Yes it can be used natively on a real C64 to run Atari 2600 programs.
If you use it within in VICE it is emulation within emulation.

I read the thread on emulation vs simulation and agree with the idea that cycle precise software emulation is real emulation.

Here's an example of Atari 2600 simulation and emulation in context:

The first Atari 2600 Flashback model used a NOAC Nintendo-on-a-chip with simulated Atari 2600 games that were actually Nintendo games programmed to look like Atari games.

Successive Flashback models used an Atari2600-on-a-chip and emulators for real Atari games.

GameLoader is cycle precise and pixel perfect. I've updated the site with side-by-side examples to try in Atari 2600 and Commodore online emulators.

Always reminds me of the discussion I had years ago with the Boeing engineer in charge of flight-testing aircraft prototypes and/or design changes to production aircraft. He wryly pointed out the difference between simulation and emulation by pointing out that a pilot can “crash” the simulator and be able to write a report about it. Not so with the “emulator” (actual plane).

All interesting perspective.

The Commodore 64 has the same BASIC I/O ports for Joysticks and RF Television output as the Atari 2600.

The same Cartridge port is not present, but GameLoader emulation solves this by dumping and recompiling the source which is also necessary to add Commodore graphics to Atari games.

I worked on the Development Team for the Retron77 emulated Atari console which inspired this idea by including a cartridge port that dumps the cart ROM into the emulator.

GameLoader emulation also includes a soft ANTIC chip that I designed. All the advanced Atari 2600 demos being emulated have the soft ANTIC chip too, but it is only a virtual chip with no hardware behind it like the Atari 400/800/5200 so perhaps it is more concept emulation of Display Lists.

I consider both the soft ANTIC and the soft TIA implementation on the C64 close emulation, since Atari 2600 demos run unchanged with precise timing.

I enjoyed your article on 6502 interrupt variations.

I was surprised to see FluidCity, one of the fastest Atari 2600 games, jitter on the Rectron 77 with an intermittent screen roll that does not happen on the real hardware. An interrupt from the Linux OS running the emulator is doubtless responsible. I saw the same problem developing the C64 Atari emulator and initially used an NMI to stop other interrupts.