Use a 6502 instead of 6507?

[universal2600]

Is it possibe to use a 6502 cpu in a 2600 instead of the 6507??

 

just wonering

[+batari]

They have a different number of pins, so while it's technically possible to wire one in, it wouldn't be easy.

[Sub(Function(:))]

The atari 1050 Diskdrive uses a 6507 (and RIOT). If you upgrade to a Happy/1050 laser etc drive enhancement you replace the 6507 with a full 6502 (and more memory)

 

SO I guess yes it would be possible. But the question is, what advantage would it be?

[davyK]

There's a good chance games would be completely screwed up if the 6502 instruction set took differing cycle counts....

[BigO]

You might find this interesting: http://www.baroquegaming.com/projects/superatari/super_atari_technical_details.htm

[CPUWIZ]

Sure, the Onyx Junior has a 6502 inside. I know that for a fact, I opened mine.

 

Here is a random pic from the net:

 

[Wickeycolumbus]

I've thought about doing this before, but never got the chance to. Overclocking it to the same speed as the TIA or a multiple of it would be interesting too...

 

Sure, the Onyx Junior has a 6502 inside. I know that for a fact, I opened mine.

 

Does it have the same memory map as a regular 2600?

[SoundGammon]

The 7800 uses a 6502 for both 7800 games & 2600 games...

[Bakasama]

Okay, I get most 2600 games could work with the 6502. Does it mean those games won't get some kind of benefit unless the games were programmed/hacked to take advantage of the 6502?

Edited February 26, 2012 by Bakasama

[31336haxx0r]

The 6507 is just a downgraded 6502 in that is has less pins. Pins used to cost a lot of money back in those days. I see no point in replacing the 6507 with a 6502, from the end user point of view although it would be nice for programmers to have much more memory.

[Bakasama]

So a Harmony cart and a 2600 modded with a 6502, wouldn't that be a system suited for developing games?

[potatohead]

Not really. The difference in pins means a difference in addressable memory. In the case of the 2600, the addressable memory is on the RIOT chip, and in the cartridge. If somebody were to build out a 2600 like system with extra RAM, there would be advantages. Then again, the Harmony brings many of those same advantages, due to how it can feed the 2600 from a very large storage on cart.

 

Developing games on a 2600 with Harmony is pretty slick, and people use emulators too. That's nice too, because it's very fast.

 

When special hardware is involved, most people don't end up with it, which limits development potential. Harmony is brilliant because it's basically a cart, and it just plugs in, meaning far more people can have one, boosting development potential.

[Tickled_Pink]

From my recollection the only difference is the number of address pins. Other than that, they're identical.

 

What would be interesting would be a 2600 rigged with a 65c02 and have a game rewritten to use the extra instructions.

[maiki]

And how about replacing 6507 with 6510?

[Matthew]

How about replacing the 6507 with an Intel 8080.

 

It would make for a fun community project to port the 2600 library to the 8080 instruction set.

[Rybags]

65C02 - probably pointless. You gain some handy instructions like INA and BRA but many games wouldn't work since many illegal ops don't work as with 6502/6507.

 

6510 - locations 0,1 are for the onboard I/O port as well as TIA which would rule it out. Aside from that, no advantage at all over stock 6502.

[Wickeycolumbus]

How about replacing the 6507 with an Intel 8080.

 

It would make for a fun community project to port the 2600 library to the 8080 instruction set.

 

That would be pretty hard and probably not fun (at least for most people, especially since there is really no point). Assuming you could interface the 8080 and TIA/RIOT correctly, you'd never be able to rewrite kernels in the new instruction set gracefully. Game logic wouldn't be easy either.

 

6510 - locations 0,1 are for the onboard I/O port as well as TIA which would rule it out. Aside from that, no advantage at all over stock 6502.

 

Also, no RDY pin.

[universal2600]

You might find this interesting: http://www.baroquegaming.com/projects/superatari/super_atari_technical_details.htm

 

 

I've thought about doing this before, but never got the chance to. Overclocking it to the same speed as the TIA or a multiple of it would be interesting too...

 

 

 

Does it have the same memory map as a regular 2600?

 

 

Sure, the Onyx Junior has a 6502 inside. I know that for a fact, I opened mine.

 

Here is a random pic from the net:

 

 

 

65C02 - probably pointless. You gain some handy instructions like INA and BRA but many games wouldn't work since many illegal ops don't work as with 6502/6507.

 

6510 - locations 0,1 are for the onboard I/O port as well as TIA which would rule it out. Aside from that, no advantage at all over stock 6502.

sorry necrobump!!!!

 

 

Hello everyone,

I'm in the process of building a 2600 from scratch, replacing the 6507 with 6502 and adding 32k of extra ram like the super Atari project, but an eBay 6502AP (http://ebay.to/2DzjYJC) should work, or are these new chips like 65c02 in that the silicon has been altered due to "modern reasons"? And what's the highest clock speed available on a 6502?

 

Also can you place an asynchronous buffer [cy7c408a] (http://bit.ly/2HGAAlm) between the data lines on the tia and 6502/7, since the [cy7c408a] is dual port with asynchronous R/W, can you just clock the output [data] bus with the TIA cpu clock, and thus should allow one to overclock the 6502 (a vcs with up to 35Mhz 6502? hmm..) with a multiple of the [ntsc] color-burst clock [ i.e having 684 cpu cycles per scan-line {using a 6502 @ 10.75Mhz } instead of just 76, I would also assume having the TIA only reading the buffer @ 1.19 would present a bottleneck as well? Can you just fill up the buffer with 128 bytes of TIA data, then handle the TIA addressing, and just fill the buffer when its being emptied?

 

Or I have a few pic micros laying around unused and since with a pic18f4550 micro instructions take effectively 1 cycle to load and execute or decode and execute, except iirc when changing the program counter which iirc takes 2 - 3 cycles, So you don't have to add wait states [i.e try to use a z80 in a 2600 which take 2+ cycles per instruction iirc].

 

Can it be used instead as sort of display controller for the tia having the 4550 handle reads from the buffer instead and handle the addressing of the TIA, as well as emulating the RIOT. [ 4550 has 32k of flash, 2k ram, and 256 bytes of eeprom]

Is it possible to emulate the Riot but with 512 bytes of ram instead of 128 bytes? Then you'd have 1.5k of ram left for handling joysticks, timing and updating the TIA, ontop of the 32k of extra ram.

 

Also if i just use the fifo buffer and if you clock it's output at the normal 1.19Mhz but overclock the cpu, i assume there will be a speed bottleneck, since you can write data faster than its being read? plus is it possible, using a12 and a15 with a 74hc138 and a logic gate or two as a way to partially decode addresses to swap between cartridge space and 32k ram, so one can simply keep native compatibility, simply if A12 is high and A15 low then cartridge ROM is accessed, and if A15 is high in any case Ram is Acessed?

 

just building it to just play 2600 games isn't really hard, and seems a little redundant, I just figured since you can build your own 2600 compatible hardware clone for less than $50 in parts shipped, why not beef it up for some shits and giggles like a dev kit, have 256k of flash eeprom and 32k ram, 6502, pic4550 as a "Hardware Kernel" aswell as emulate the riot, And CO10444D fits snug on 8 x 10 cm pcb. why you ask? Because i i'll have the only atari "super" VCS with full USB 2.0 support (upto 12Mbit/s lol) and plus i can really push the TIA to the limit see what it can do with some "power" behind it