Emotional stories about processors for first computers: part 9 (Acorn ARM)
The first ARM processors
The ARM-1 processor was an astonishing development, it continued the 6502 ideology (namely to make a processor that is easier, cheaper and better), and was released by Acorn in 1985. This was at the same time when Intel's technological miracle the 80386 processor appeared. ARM consisted of about ten times less transistors ( Read more... )
The ARM-1 processor was an astonishing development, it continued the 6502 ideology (namely to make a processor that is easier, cheaper and better), and was released by Acorn in 1985. This was at the same time when Intel's technological miracle the 80386 processor appeared. ARM consisted of about ten times less transistors ( Read more... )
Removing freedom to the programmer in assembly language is indeed heresy. Very true ! However with this logic every RISC design in the world is heresy, of course including the ARM.
By comparison, the "removed freedom" on the 68k is very limited. And it allowed short encodings while keeping a powerful instruction set.
Sure, i can concede that the D/A split is too strict on the 68k. But it is nowhere as bad as was said.
So oring and anding pointers is useful for graphics operations ? This requires example code, because it sounds totally crazy !
And perhaps you should also tell this secret to C compiler writers, as they obviously don't know - and there is no reason something useful in asm shouldn't be useful in other languages as well.
About ARM's code density never being more than 15% bigger than the 68k, try to do something large, with lots of memory accesses - especially 16-bit ones - and see where it goes.
But all of this is just talking. Only facts can settle this.
x86 code density pretended being better than 68k has already been showed wrong.
So, ready for a code contest ?
It should be easy against someone who doesn't know what he's doing !
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On the Archimedes it is the way you set the DMA addresses ;-)
https://books.google.fr/books?id=RkxnDwAAQBAJ&pg=PT121&lpg=PT121&dq=arm+memc+memory+bus&source=bl&ots=6wrL786biL&sig=3AJDM3K532mxk2qYGYENgUEY2RM&hl=fr&sa=X&ved=2ahUKEwjMiIv7uPHeAhVJXhoKHW5cDy8Q6AEwBXoECAIQAQ#v=onepage&q=arm%20memc%20memory%20bus&f=false
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Worse, on a multitasking machine like the Amiga, user program memory addresses change and logic operations are just meaningless (and the hardware does not need anything like that).
However it's true that ARM does not have a complex index addressing mode and this needs to be compensated somehow...
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arm memc memory bus
ORRing pointers on the ARM does make sense
for the Archimedes and RISC PCs etc ... to set the MEMC DMA values,
and the VIDC registers values too.
;-)
I have answered about ANDing addresses in the previous post,
and the benefits of building addresses for the PC, at will, with no constraint.
Try harder next time to state I don't know what I am talking about,
so far your comments make me burst out laughing.
Reading your BS on eab is like going to the zoo.
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And your insults do not help in having you looking like a serious guy, more like a troll.
Too bad. You're the only one i've found who defends arm asm programming and it would have been otherwise enjoyable to discuss.
Tell me if you're ready for some more discussion about this.
And please stop this name-calling nonsense, it's the reason why you got banned from EAB (look at litwr, he writes quite some nonsense all day long, but didn't even got a warning because he's not aggressive like you are).
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