define instruction from easy 6502 not working #7
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Which assembler are you trying to use? Each assembler does have unique choices for how to express a program, and easy6502 is no exception! |
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I tried downloading the 6502 JS Assembler, it would not recognize the
Define instruction as used in the tutorials.
…On Wed, Nov 22, 2017 at 8:12 AM, BigEd ***@***.***> wrote:
Which assembler are you trying to use? Each assembler does have unique
choices for how to express a program, and easy6502 is no exception!
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Do you mean http://www.6502asm.com/ ? If so, it has no define, so from the examples we see the tactic is to use a label: |
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Oops sorry I have just realised that I was confused between easy6502 and 6502js. Let me look into this. We do know the two assemblers have diverged. My own fork of 6502js is different again. |
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OK Cool thank you, yeah I was hoping that there was one of these I could
download to practice assembly on my own, like building snake from scratch
with the embedded screen you guys had in easy 6502
if this is possible, plz lemme know, I know easy6502 had a define
instruction for their snake example
…On Sun, Nov 26, 2017 at 9:55 AM, BigEd ***@***.***> wrote:
Oops sorry I have just realised that I was confused between easy6502 and
6502js. Let me look into this. We do know the two assemblers have diverged.
My own fork of 6502js is different again.
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for example, trying to use the easy 6502 assembler downloaded from easy 6502
in the tutorial, they use (define) as a means of declaring
constants/variables. Upon downloading the Assembler though, the define
instruction stops working. How would I still define variables/constants?
…On Sun, Nov 26, 2017 at 4:11 PM, Raymond Liberto ***@***.***> wrote:
OK Cool thank you, yeah I was hoping that there was one of these I could
download to practice assembly on my own, like building snake from scratch
with the embedded screen you guys had in easy 6502
if this is possible, plz lemme know, I know easy6502 had a define
instruction for their snake example
On Sun, Nov 26, 2017 at 9:55 AM, BigEd ***@***.***> wrote:
> Oops sorry I have just realised that I was confused between easy6502 and
> 6502js. Let me look into this. We do know the two assemblers have diverged.
> My own fork of 6502js is different again.
>
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> You are receiving this because you authored the thread.
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> <#7 (comment)>,
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Just started looking at this. I see you can use the same kind of workaround, abusing the label mechanism to define a symbol: |
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How would you use this technique in something like a constant? Lets say for
example I wanted to set sysRandom = $fe (the RNG on the mock 6502)
*=255 - is this setting mask to 255 decimal? I'm a little confused as to
how this example works in practice, thanks for the help
…On Mon, Nov 27, 2017 at 1:01 PM, BigEd ***@***.***> wrote:
Just started looking at this. I see you can use the same kind of
workaround, abusing the label mechanism to define a symbol:
* = 255
mask:
* = $600
start:
nop
lda mask
nop
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Here's a slight expansion of the example: and the disassembler says we got this: So, it's a little ugly, and it takes two lines to make each define, but I think it works generally. |
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(However, I notice the tactic fails for immediate values. I should have written |
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Aghh that's unfortunate, was going to use this idea for costants related
to collision, if there's a workaround, kindly let me know, thx!
…On Nov 27, 2017 13:33, "BigEd" ***@***.***> wrote:
(However, I notice the tactic fails for immediate values. I should have
written
lda #mask
but that turns out not to work at all.)
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oh and just for context, I'm trying to build snake/pong in the assembler
without using the help of the tutorial, so i assume even if reformatted for
the above hack, that code still wouldnt assemble given the #immediatevalue
error.
…On Mon, Nov 27, 2017 at 1:35 PM, Raymond Liberto ***@***.***> wrote:
Aghh that's unfortunate, was going to use this idea for costants related
to collision, if there's a workaround, kindly let me know, thx!
On Nov 27, 2017 13:33, "BigEd" ***@***.***> wrote:
> (However, I notice the tactic fails for immediate values. I should have
> written
> lda #mask
> but that turns out not to work at all.)
>
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I think we'd need to bring the whole 'define' mechanism in from easy6502 to 6502js. Meantime, could you work using a local copy of easy6502 instead of using 6502js? I tend to try out small snippets just using the first emulation window - the snake is way down the file and needn't distract you. |
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Yes that would be perfect, could you link me to the appropriate place to
grab the easy 6502 engine? Tha k you so much
…On Nov 27, 2017 13:57, "BigEd" ***@***.***> wrote:
I think we'd need to bring the whole 'define' mechanism in from easy6502
to 6502js.
Meantime, could you work using a local copy of easy6502 instead of using
6502js? I tend to try out small snippets just using the first emulation
window - the snake is way down the file and needn't distract you.
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Oh wait I see what you mean, yeah that sounds good, please keep me posted
as to when you add in define. Also curious, how do I reserve bytes for
variables? For the nes, all I usually will do is (nesasm)
ballspeedx: .rs 1
…On Nov 27, 2017 13:57, "BigEd" ***@***.***> wrote:
I think we'd need to bring the whole 'define' mechanism in from easy6502
to 6502js.
Meantime, could you work using a local copy of easy6502 instead of using
6502js? I tend to try out small snippets just using the first emulation
window - the snake is way down the file and needn't distract you.
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Reserving some bytes... I think the effect will be to set the label and then for the next label to take a slightly higher value. So perhaps just use dummy code sequences instead: |
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I made a fork of the emulator here and fixed the issue partially. the following would now work : I haven't yet managed to make it work in indexing modes though, so would not assemble, assuming value is a constant defined by the |
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Assembler doesn't recognize the same instruction from the tutorial
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