Thread: ASM: Resources
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Old 30 December 2014, 01:00   #43
Ultron
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Join Date: Feb 2006
Location: Amigaland, Nostalgia
Age: 44
Posts: 757
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Quote:
Originally Posted by bippym View Post
A good looking 68k ASM guide. The author does megadrive programming, but this is pure 68k http://mrjester.hapisan.com/04_MC68/
Quote:
Originally Posted by Photon View Post
Disagree strongly, and the very scarce examples were confusing. I happened to click on "The ADD instruction" and the author goes into some silly talk about base16...
Quote:
Originally Posted by bippym View Post
Now I have read it fully I am inclined to agree.. He explains the usage of a few commands, but there are no real examples or tutorials.

Deleted from first post!


"A good looking 68k ASM guide"

It IS a very good 68k ASM guide.

Perfect for people who know nothing going in. People who come from C or other high languages. It's simple. It demystifies Assembler. It's very well explained and easy to understand, i don't even think i've even seen better. It litterally guides you through bits, bytes, word, etc in a very simple and easy to understand manner, making you understand everything that makes a computer tick: binary\bit operations. It's very complete too, and the adresses m68k instruction set thoroughly.
PHOTON: "Disagree strongly, and the very scarce examples were confusing. I happened to click on "The ADD instruction" and the author goes into some silly talk about base16..."
From the website :
(http://mrjester.hapisan.com/04_MC68/...t01/Index.html)

By now you may understand that FF is the highest number in a byte (in hex), just like 99 is the highest number out of a 2 digit decimal number. Adding 1 to 99 (in decimal) results in 100, for hex it would be the same thing, adding 1 to FF (in hex) results in 100.

But in the above examples, you may notice the example of “if d0 started with 222222FC”. You may think that adding 8 would result in 22222304, and this would normally be correct. But remember, we’re only adding a byte, so only the right byte is affected, and the nybble “2” is not increased by 1.

What's silly about any of this?

It's completely true.

And a person must understand the impact and different outcomes of ADDing either a byte, or a word, with two completely different consequences and outcomes.
Byp: "Now I have read it fully I am inclined to agree.. He explains the usage of a few commands, but there are no real examples or tutorials.

Deleted from first post!"
Seems like bowing down to a superior authority by reaction, he's completely wrong and you were completely right.
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