6502 Tips, Tricks and Links

Talk about programming CreatiVision (except games programming). Projects of homebrew hardware are also welcome.
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TBCTBC
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6502 Tips, Tricks and Links

Post by TBCTBC » Wed Apr 10, 2013 9:23 am

Thought I would make a thread with some useful information for programming the 6502.

Links

http://6502.org/tutorials/6502opcodes.html
I find this page pretty useful when I need to look up something.

http://www.emulator101.com/6502-addressing-modes/
This page explains the addressing modes in a nice way.
I found this when I needed to understand how indexed indirect works.
I use indirect indexed pretty often, but never indexed indirect.

http://www.ataripreservation.org/websit ... lopc31.txt
A little text describing the illegal opcodes of the 6502. Maybe you shouldn't be using them, but it's fun :)
I'm not sure how accurate this is or if there's a better page out there.

Does anyone else got any nice links?
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MADrigal
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Re: 6502 Tips, Tricks and Links

Post by MADrigal » Wed Apr 10, 2013 11:31 am

This is extremely useful information for people like me, trying to learn the 6502 programming.

Much appreciated :)
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Mobsie
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Re: 6502 Tips, Tricks and Links

Post by Mobsie » Thu Apr 11, 2013 6:47 am

I give a lot people this link:

http://www.6502asm.com

Is a complete Online Emulator with a lot samples.
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MADrigal
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Re: 6502 Tips, Tricks and Links

Post by MADrigal » Thu Apr 11, 2013 12:00 pm

Mobsie wrote:I give a lot people this link:

http://www.6502asm.com

Is a complete Online Emulator with a lot samples.
Wow it's gorgeous!! :-D
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carlsson
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Re: 6502 Tips, Tricks and Links

Post by carlsson » Thu Apr 11, 2013 1:20 pm

TBCTBC wrote:I needed to understand how indexed indirect works.
Have you ever found a use for that addressing mode, some kind of jump table in zeropage?

The irony is that indirect indexed mode ($nn),y is a staple, something you use very often for dynamic programming and perhaps even more so when dealing with mostly ROM oriented software, while indexed indirect mode ($nn,x) is something I still really haven't found a reason to use.
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Mobsie
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Re: 6502 Tips, Tricks and Links

Post by Mobsie » Thu Apr 11, 2013 1:57 pm

Yes i also use only indirect indexed mode.

For example in my tile-map engine i use tables with the direct screen address to send to the VDP reg.
And for all kinds of calculation or shifting.
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TBCTBC
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Re: 6502 Tips, Tricks and Links

Post by TBCTBC » Thu Apr 11, 2013 2:26 pm

carlsson wrote:
TBCTBC wrote:I needed to understand how indexed indirect works.
Have you ever found a use for that addressing mode, some kind of jump table in zeropage?
Nope, it's almost useless :) I thought I could use it for something, but it turned out I didn't need it.
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