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Apple II on an FPGA
http://forum.6502.org/viewtopic.php?f=10&t=1962		 Page 1 of 1
Author:  TMorita [ Sun Oct 16, 2011 7:02 pm ]
Post subject:  Apple II on an FPGA
I was googling for some unrelated stuff, and ran across this web page:

\http://www.cs.columbia.edu/~sedwards/apple2fpga/

Maybe some of the files from it should be added to the archives?

Toshi
Author:  ElEctric_EyE [ Tue Oct 18, 2011 10:39 pm ]
Post subject: 
He references the Syntiac pages, where he got Peter Wendrich's 6502 (6510?) core. I've been to that site before and assumed he was no longer sharing his CPU core because he had moved it out of the VHDL library. But they're easily accessible in the zip files.
That site and FPGAARCADE's site are very inspirational for FPGA enthusiasts like me. New update on FPGAARCADE, been almost 4 months!
Author:  ElEctric_EyE [ Wed Jul 10, 2013 11:38 pm ]
Post subject:  Re: Apple II on an FPGA
Ah, here we go. This is the thread I was looking for!
Another update on FPGAARCADE.

Congrats to Mike for apparent completion of his Replay Board.
Author:  enso [ Thu Jul 11, 2013 4:35 am ]
Post subject:  Re: Apple II on an FPGA
I made an Apple ][ a couple of years back. The verilog is really ugly, but it does work. It's a bit of a blur and I wish I took more notes. I can't even remember how to put the files onto the SD card anymore, but I have 128 games I can select from... I am afraid to touch it as I don't think I'll be able to fix it if it breaks...

I used Arlet's core on a XESS board, my own VGA design and a bunch of horrible glue connecting it all up. I had to breadboard a couple of 556 timers for joysticks. a speaker, an SD card and a rotary sensor for selection (controlled by a picoblaze).

It was definitely an interesting project.

There is also this link: http://alexfreed.com/FPGApple/revisited.html
Author:  enso [ Wed Jul 17, 2013 4:49 am ]
Post subject:  Re: Apple II on an FPGA
I unpacked it and it still works...
Attachment:
myapple.rotated.JPG
myapple.rotated.JPG [ 302.5 KiB | Viewed 3211 times ]

What's really interesting is that pretty much all games I've tried to run on it run. A few refuse to run (probably has to do with writing to disk - I don't support it). Only one, Apple Panic, works but the image of the little guy running around is scrambled. It's probably one of the weird undocumented instructions. I am surprised how rarely they must be used. I know I've been tempted back in the day.
Author:  TMorita [ Sat Jul 20, 2013 6:48 am ]
Post subject:  Re: Apple II on an FPGA
The Apple II line included the Apple //e, which used a 65C02.

On the 65C02, the undocumented opcodes are NOPs if I remember correctly.
So any software using undocumented opcodes would not run on the //e.
So people avoided using the undocumented opcodes.

Also, I don't think the Apple II assemblers such as Merlin, LISA and S-C Macro Assembler supported the undocumented instructions.

Toshi
Author:  GARTHWILSON [ Sat Jul 20, 2013 7:04 am ]
Post subject:  Re: Apple II on an FPGA
Quote:
The Apple II line included the Apple //e, which used a 65C02.

On the 65C02, the undocumented opcodes are NOPs if I remember correctly.

The Apple IIc used the 65c02 also. Many of the undocumented op codes on the NMOS 6502 became other [documented] things on the 65c02 which had more instructions and addressing modes; so the undocumenteds of the NMOS would do something different on the CMOS.
Author:  enso [ Sun Jul 21, 2013 5:31 am ]
Post subject:  Re: Apple II on an FPGA
Your are correct, it cannot be undoc'd instruction. This makes the mystery even more interesting. If your are unfamiliar with Apple Panic, it is a simple game in which you control a little guy runing around several horizontal I-beams connected with ladders while bad apples are trying to eat you.

The blitting works fine for the apples, but the guy is messed up. I think it actually comes out as a white block. I haven't seen that anomaly in any other game I tried.

I will pull up the game and take a picture in the next day or so.
Author:  enso [ Sun Jul 21, 2013 11:08 pm ]
Post subject:  Re: Apple II on an FPGA
I was wrong about the anomaly... It is even weirder then what I thought!

The image of the running guy is fine, but it does not get erased, leaving a trail of shapes behind it...

My camera's battery died; I will add a picture as soon as I can.
Author:  enso [ Wed Jul 31, 2013 7:26 pm ]
Post subject:  Re: Apple II on an FPGA
Here is a photo. The little guy just leaves a trail behind him. This is the only game I found that fails in this particular way. One possibility is that I used Arlet's core from a couple of years back, probably before he found a few issues using a test suite more recently.
Attachment:
DSCN1433.resized.JPG
DSCN1433.resized.JPG [ 111.5 KiB | Viewed 3089 times ]
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