A crazy idea..

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Joined: Mar 23 2005
Posts: 19

The Apple 1 had a lot of unused space that could be filled with whatever you wanted, that was the beauty of the thing--a beauty that was lost to some small degree in the later Apples, which had a lot more structure to them. You just couldn't do as much to them without giving up compatibility. That's not much of a problem with the Apple 1..

So I started thinking about improving the video of the Apple I. Since the video stuff is being emulated using more modern hardware anyway, why not stick the ability to go overboard a bit into some memory space that isn't currently used and ... go overboard with the video? Some graphics techniques used by other 6502-based computers could be employed, as could some of the tricks of game consoles like the NES..

Then it hit me. We've already seen a few products that put a full, working NES on a single chip, right? One of them was quasi-legitimate (they didn't exactly ask Nintendo for permission, but the thing emulated the hardware, nothing more..) All of the others, of course, are CPLD type devices with a boatload of crappy bootleg ROMs burned in. For moral reasons, I refuse to acquire one of these latter types, but it got me to thinking.. The techniques used to recreate the parts of the Apple 1 that you just can't buy anymore could be used to recreate bits of the NES, the C64, and whatever else.

Anyone else considered a multisystem project? Even just the Apple 1 and Apple ][+ or so?

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Joined: Mar 9 2005
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Rather than use a CPLD you co

Rather than use a CPLD you could use a SBC like the TS-7200 from Technologic systems. A 200MHz ARM emulating an Apple 1 would be fast. You could then make it a multi system emulator, to run macintosh, apple IIe, Apple IIGS, etc.

http://www.embeddedarm.com/epc/ts7200-spec-p.php

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Joined: Mar 23 2005
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Re: Rather than use a CPLD you co

logjam wrote:

Rather than use a CPLD you could use a SBC like the TS-7200 from Technologic systems. A 200MHz ARM emulating an Apple 1 would be fast. You could then make it a multi system emulator, to run macintosh, apple IIe, Apple IIGS, etc.

http://www.embeddedarm.com/epc/ts7200-spec-p.php

But that's an emulator. I can emulate an Apple //e on my G5. I do emulate an Apple IIgs on it. Emulators almost universally fail to provide accurate timing. Either they try (and fail) or they end up running full out and are too fast.

I wasn't thinking about using a CPLD necessarily as much as I was thinking that the same sort of recreation of missing parts done for the Apple 1 could be done for other 6502 projects.

I just think it would be damned cool to shove a Mario 3 cart into a Replica 1 and reset into a different hardware mode and start playing. Wink

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Joined: Mar 9 2005
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Yes, I agree on the emulator

Yes, I agree on the emulator part. Putting an Apple 1 into an FPGA is an emulator, and even putting some of the circuits in a CPLD is a type of emulator. The replica emulates most of the Apple 1 hardware...

cbmeeks's picture
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Joined: Jan 17 2005
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Re: Rather than use a CPLD you co

knghtbrd wrote:
logjam wrote:

Rather than use a CPLD you could use a SBC like the TS-7200 from Technologic systems. A 200MHz ARM emulating an Apple 1 would be fast. You could then make it a multi system emulator, to run macintosh, apple IIe, Apple IIGS, etc.

http://www.embeddedarm.com/epc/ts7200-spec-p.php

But that's an emulator. I can emulate an Apple //e on my G5. I do emulate an Apple IIgs on it. Emulators almost universally fail to provide accurate timing. Either they try (and fail) or they end up running full out and are too fast.

I wasn't thinking about using a CPLD necessarily as much as I was thinking that the same sort of recreation of missing parts done for the Apple 1 could be done for other 6502 projects.

I just think it would be damned cool to shove a Mario 3 cart into a Replica 1 and reset into a different hardware mode and start playing. Wink

There is already a system that is going towards what you are talking about. It's the Commodore C-One

http://c64upgra.de/c-one/

It has a lot of promise.

-cbmeeks

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Joined: Mar 23 2005
Posts: 19
Still looking for video options

cbmeeks wrote:

There is already a system that is going towards what you are talking about. It's the Commodore C-One

http://c64upgra.de/c-one/

It has a lot of promise.

-cbmeeks

Yeah, I saw it, but it wouldn't load for me before today. (So I saw a google cache), but the thing about this system that makes it somewhat uninteresting to me is its price. Those FPGAs are expensive, even if they can do lots of cool things. You also see that they're working with a lot of SMD components. I frankly don't have the eyes for that.

My insanity level has reduced slightly and now I'm just looking for a way to get a colour graphics display in a form that is not SMD and hopefully neither hideously complex or hideously expensive. I've seen some really (really!) low resolution stuff that I may be able to get cheaply, but these were monochrome, and 64 pixels isn't much for monochrome.

If I better understood the video stuff done up for the Replica-1 I would wonder about possibly using a bigger microcontroller and some video SRAM, then just have the microcontroller poke at it only when the 6502 isn't.. For my personal use, VGA compatible timings would almost be more useful, but I think I'd best stick with composite since there's at least a chance I can figure out how that works well enough to consider how to add colour and the colourburst singnal..

The madness with the NES rose from trying to imagine what would be a good graphics controller that I might be able to both get and actually use. I have no idea what was in the NES, but the graphics it does are perfect for all intended purposes. =)

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Joined: Apr 27 2005
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Video Considerations....

It's quite intresting to understand why Woz used a Character-only
video output...

It's all about RAM Smile ... 1K of RAM is all you need to get letters on an apple I.

if you try to get graphics, the amount of RAM used it's huge,
and by the time Woz was creating the Apple I, RAM was not exactly cheap...

600x400 pixels on a B/W screen are 30K bytes already,
600x400 pixels 8bit color: 240K bytes

1MB RAM is not expensive now a days, but still, the 6502 is not fast
enough for using 1Mb on a single screen, so we need video pages,
scheduling, retracing, etc. and the task turns into a non trivial challenge Smile

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Joined: Mar 23 2005
Posts: 19
Sure enough, but these days R

Sure enough, but these days RAM is dirt cheap, and the hardest part about doing color video is avoiding surface-mount soldering of the chip to combine RGB signals.

I was looking at 4 bit 320x200 possibly, or even something like the NES tiler engine. If I could get such a thing in a form factor I can use (I'm working with kids who won't be allowed to solder, so I'm having to design this for wire-wrap), it'd be cool.

shiftkey's picture
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Joined: Feb 10 2005
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HA Now here's an idea!

How about an Apple I on a CHIP! Complete with Casset interface hookup! No external things needed... just a keyboard, a monitor, and a tape drive.

HEY! Why did Apple not bother putting BASIC directly into the ROM. Was it too small?

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BASIC in ROM?

The Apple I didn't have BASIC in ROM because:
A. ROMS were expensive.
B. BASIC was not considered to be very necessary. Those guys were computer pioneers and nobody thought computers would ever catch on like they have. Most used their computers to run efficient Assembly Language programs.
C. Heck, it only takes a few minutes to dump BASIC into your computer from your cassette, so why go to the trouble.

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shiftkey's picture
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Hmmm...

well they still used a ROM... Woz Monitor was in it, rememeber?!

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Shiftkey

iceandfire's picture
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Apple I ROM

The monitor in the Apple I was only 256 bytes and still had to be on two chips, each 256 X 4 bits. ROMS were relatively expensive and hard to program. And yet, the Apple was the leader. Most microcomputers at the time did NOT have a monitor. Each time you turned the computer on, you had to load the bootstrap program into RAM, one byte at a time.

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Larry Nelson