applekevin

What percentage of them would you say are useful?

As I understand it, the majority just produce erratic behavior. Which of these were worthwhile? Also, does this set differ in the 6502C SALLY from other 6502 variations?

Ricortes, Thank you for that link! That was exactly the sort of thing I was referring to. Also, I know that the 65816 boot up in emulation mode. What I meant was that I was wondering if it was possible to trap illegal ops that were useful in software.

Could the illegal instructions be "emulated" with the new, legal instructions in the 65C02?

So, apart from the fact that the the A8 bus is designed around a 1.79mhz processor, as I understand it, the main difficulty in making a an accelerator for the Atari is the incompatbility between the 6502C/SALLY (not to be confused with the 65C02) and the 65C02 and 65816, which lack support for the illegal opcodes present on NMOS 6502s. It's my understanding that this is roughly analogous to the problem in the Apple II world with the Apple IIc, where the IIc's 65C02 can cause a lot of incompatibility problems. Basically, I had three ideas and was wondering whether these would work. Would it be possible to write a program to patch 'dirty' software which utilizes illegal opcodes to work with "clean" implementations? Furthermore, would it be possible to use some sort of static recompilation to take advantage of the extended instruction set of the 65C02, to make up for potential performance loss due to the loss of the illegal opcodes, or to improve already working software? For the Coldfire, there is some software called CK68klib. Basically, the Coldfire is a stripped down version of the 68k. Most CF code is compatible with 68k processors, but not the other way around, since the CF instruction set (I think) is basically a subset of the 68k instruction set. What CK68klib does is basically 'trap' opcodes that don't exist on the CF and convert them to work with it on the fly. Obviously, there is a some performance penalty, but a CF v4 can actually outperform true 68k processors, even with this. Would such a thing be possible for the 65816? Lastly, if a software option isn't possible, or at least wouldn't be at all practical (obviously since bother are turing machines, it is theoretically "possible," in the same way emulating a PS3 on the A8 is "technically possible" but pointless!) could some sort of CPLD or FPGA be used to decode illegal opcodes into legal ones on the fly? Thanks for reading! Sorry if my questions are dumb or don't make sense!

I honestly think the best option would a Coldfire V4 + CK68klib. This is the cheapest way, IMO, to get a real 68k processor. They can be had for less than $10 (BGA only though). For graphics. . .hmm, well, one kind of crazy option would be some sort of vector coprocessor. In fact, there is a BSD-licensed clone of the Cray-1 which apparently runs at about 50mhz (compared to the 80 of the original). There's also the SuperVIDEL, but it's closed source. For sound, something on par with the Yamaha OPL4 might be nice.

I know this topic has been probably done to death, but I didn't see any threads on it, so why not. Basically, what features would you want in a followup to the ST/TT/Falcon series? I know there's the FireBee, but the price is so astronomically high, it will necessarily remain an ultra-niche product. I have basically three things I would want: Above everything else, an OpenHardware design. The Ataris and Amigas are living testaments to the danger of proprietary designs. This is even more a problem for low-volume things like a new Atari would be. Under $100. I don't even know if this is possible, but then again, FPGAs are going down in price. . . Can be made by hand. The circuitry should be such that it could be soldered by an individual with adequate skill. While I doubt it's possible, what would be even better is if the PCB could be made with only 2 layers, then even it could be DIY'd

wow! awesome thanks so much! Looking at the PCB. . .urgh, it looks like a custom chip Oh well, there goes that. Then again, I suppose I could use some sort of CPLD, but at that point. . .the harmony would be less hassle anyway.

Yeah, I remember reading that. IIRC it involves some sort of simple IC (I think a 74xx series). Do you (or anyone else for that matter), at the very least, know where I could find images of the supercharger PCB?

I was wondering if anyone has the schematics to the supercharger and/or can provide any info on what it had in it's guts. Would it be possible to build a clone of it inside a regular sized cartridge? I know there is the Harmony cartridge, but that's a bit out of my budget ATM, and I'd like to play around with this anyway. EDIT: Well, I feel stupid for having posted that, as I just found the schematics after about 30 seconds of Googling! (Located here http://www.atarihq.com/danb/images/superch.gif for those who are wondering). Anyhow, looking at those, it's really unclear to me what's actually inside. Obviously some RAM chips, but other than I can't tell. Some sort of rudimentary programmable logic? Wouldn't there need to be some sort of basic ADC for the converting the audio?

I've been thinking about building a portable 2600, but the thing bothering me is the battery life question. AFAIK, all 2600s use an NMOS processor, because the CMOS chips are missing illegal opcodes. Is the junior the same as the other 2600s? I'd consider using an FB2, but is the compatibility any good? I know you can't use the supercharger or the harmony cart with it. Aren't there also a lot of homebrew which don't work with it either?

Basically, I'm just looking for a plain vanilla 800XL. I don't need any peripherals or anything like that. I don't mind if it's yellowed, but I woukd prefer no broken plastic or gashes. Also, the PSU would be great Other than that, I guess a few cart games and/or a joystick would be nice to get me started but are by no means necessary.

Wow guys! Again, thank you ALL so much for your awesome answers! So, addressing the first point. I know the VBXE is not a required upgrade by any means. And I definitely won't be starting out with it. However, as I mentioned, I'm just curious whether the RGB out will work for all software, or just stuff specifically made for it. With respect to the U1MB, I saw another post talk about removing the 32-in-1 OS and replacing it with the U1MB. Now I'm confused, I thought it was RAM upgrade, but does it actually upgrade the OS? Will a PAL model run slower than NTSC because PAL is 50hz? If I replace ANTIC with a PAL model, will it work with NTSC TVs but have PAL compatibility? Finally, still confused about the SIO2xx things. As I mentioned, there appears to be both the SIO2SD and SDrive Nuxx. I can't figure out which is better. Also, what is the advantage of the SIO2PC over the SIO2SD? I don't have a PC anywhere near where I would put my Atari unfortunately.

Hmm, Well, I know there are compatibility issues across the line of Ataris, but is this one you mention different? Will that translator OS or whatever it's called that allows you play 800 stuff on an XL/XE work there, or not?

Thanks so much for your answers to all my questions!! A few things: In terms of cartridges being complicated, no I definitely understand. I'm not too much of an NES guy, but I'm vaguely acquainted with how difficult it is to build a flashcart for it due to the broad assortment of mappers. That being said, can the SIDE2 function as a sort of flashcart? Are there games/software exclusive to cartridges, and if so, is there anyway to play them without owning the originals? Now, you say get a disk drive, but isn't that the point of SIO2SD and SDrive? To emulate one? If you don't have any original disks (like me) wouldn't it be better to just go with this? I'm American, but, should I still get a PAL Atari? Obviously I would need to import it, but I do have a PAL TV somewhere around here. You say that a lot of software will not work on NTSC, but I assume that the converse is not true. Does the PAL Atari play NTSC games? Or is it like 2600 where it's basically impossible to convert between the two? Again, thanks so much for taking the time to answer my questions!