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Old 25 January 2016, 14:40   #21
spoUP
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That alcatraz demo would be interesting to test. Which part was it? And which alcatraz demo? I or II?
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Old 25 January 2016, 14:48   #22
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COOL FRIDGE by UPFRONT, gives me a black screen on the problematic part, nice find.
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Old 26 January 2016, 09:44   #23
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This is Alcatraz Mega Demo II
In the last part that start with the message "this part only works in a1000"
If I remenber well (last time i saw it 25 years ago on an A1000...) on A1000 there are vector graphics (things like rotating cube) in the midle of the screen

If remenber well what said an alcatraz coder called DarkBlitter " one of our craziest coder has tested several unused 68000 opcodes and had found one that do a math operation that serve to optimize this demo"
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Old 26 January 2016, 11:05   #24
StingRay
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Quote:
Originally Posted by thellier View Post
If remenber well what said an alcatraz coder called DarkBlitter " one of our craziest coder has tested several unused 68000 opcodes and had found one that do a math operation that serve to optimize this demo"
That's typical coder humour. There are no illegal/undefined 68000 opcodes. I don't remember that there was anything special with the last part when I made the WHDLoad patch some years ago, I'll check when I'm back home.
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Old 26 January 2016, 14:32   #25
meynaf
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Quote:
Originally Posted by thellier View Post
If remenber well what said an alcatraz coder called DarkBlitter " one of our craziest coder has tested several unused 68000 opcodes and had found one that do a math operation that serve to optimize this demo"
I tested all unused 68000 opcodes many years ago and they all trap as illegal.
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Old 01 February 2016, 01:41   #26
ReadOnlyCat
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I tested all unused 68000 opcodes many years ago and they all trap as illegal.
Good to know, thanks for sharing.

How many words of operands did you test with? I guess you had to choose an arbitrary limit just in case an illegal opcode used more than one word?
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Old 01 February 2016, 08:44   #27
meynaf
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Good to know, thanks for sharing.

How many words of operands did you test with? I guess you had to choose an arbitrary limit just in case an illegal opcode used more than one word?
As the 68000 traps as illegal by checking the first code word only, it's pretty safe to test just that (some 020+ codes are wrongly executed on '000 because of this).
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