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So disadvantages of A, X, and Y Register:

A = Cannot use INCrement nor DECrements DIRECTLY. INC and DEC only works onto Address Code.

X and Y = Cannot Transfer/"Copy-And-Paste" each other directly. ONLY through Register A.

Yes, it was a lot of info, and yes a lot of it was similar (hence feeling repeated), but that's also why I did so much. IN? adds one. DE? subtracts one. T12 copies the value from register 1 to register 2. You can't INA, you can't DEA, you can't TXY and you can't TYX. That's all 10 instructions. Tha...

Ah, so "#" and "#$" can be used. Is the binary [WAY advanced] also used like "B$"? Binary depends on what assembler you're using. I don't think Easy 6502's assembler supports binary, but ca65 uses % for binary lda #$45 lda #%01000101 Negative numbers on 6502 are repres...

This is going to be a loooong time for me to finally master 6502 and draw animations of edutainment for it.

ldx #$20 and ldx #32 both put the number 32 in register X. lda #$45 and lda #69 both put the number 69 in register A. So does lda #'E' , as the ASCII code for capital E is 69 (or $45). When we eventually get to writing text to the screen, you'll start dealing with ASCII codes . If you want to move ...

There are many cases where transferring one register to another can be useful. Like you already know, some operations can be done on some registers but not others, so you may need to load a value in one register, do something that can only be done with that register, then transfer it to another reg...

It's really pretty simple: you can think of 6502 registers as variables which can only hold values ranging from 0 to 255. The 6502 code that's equivalent to the above would be: foo = $00 ; Memory location $00 bar = $01 ; Memory location $01 qux = $02 ; Memory location $02 lda #5 sta foo ; foo = 5 l...

Yep, that's what I wanted. Now let's get most of the remaining easy instructions out of the way. But realize things will get a bit harder after this since we'll introduce new concepts. First, the "transfer" family. They're somewhat similar to the "LD?" family of instructions. Th...

Here are a few "new" instructions. "Try 'em, they're easy!" I always say most of the things one can do in 6502 have a small, and simple result. (I really mean actually try them! Use the debugger, step through, and see how the "state" of the CPU changes. They are simple...

Yeeeeesh... lda #$04 sta $0200 sta $0201 sta $0202 sta $0203 sta $0204 sta $0205 sta $0206 sta $0207 sta $0208 sta $0209 sta $020A sta $020B sta $020C sta $020D sta $020E sta $020F sta $0210 sta $0211 sta $0212 sta $0213 sta $0214 sta $0215 sta $0216 sta $0217 sta $0218 sta $0219 sta $021A sta $021B...

Opening Note: It may seem like I'm being picky on language, but I'm just really trying to make sure everything is understood. Please bear with me. lda #$02 ; The A, Accululator, is now replacing previous Register A, from number 1 into number 2. It may be better to think of it as the number inside t...

Looks good/correct except for one line: sta $0200 ; The A's content, number 2, is now being stored into Address 01 / $0001. Everything else you said is right. *thumbs up* OOoooh, typo. My bad. :oops: It's Number 2 being stored into Address $0200 / $200. There is ABSOLUTELY NO forms of advanced tech...

Homework assignment (I guess?). Comment this example code like I have done above. It may start to make more sense: lda #$01 sta $08 lda #$02 sta $0200 lda #$01 sta $05FF Then do the same for this code: lda #$01 sta $08 lda #$01 sta $0200 lda #$02 sta $05FF And the reason for the display difference ...

Hmm... there seems to be confusion on addresses and values. ... I have been reading this forum for a while and I really think you should copy some of your responses to the Wiki. Sections like http://wiki.nesdev.com/w/index.php/Programming_Basics are still half empty, and your explanations are lengt...

Hmm... there seems to be confusion on addresses and values. The Accumulator (or A) contains a single 8 bit value. The accumulator is WHERE the value is stored. The value is WHAT is stored in the accumulator. RAM is a series of 8 bit values. Each "address" of RAM refers to a specific conta...