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May 20, 2013, 11:49:52 AM
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ethicalhack3r
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 « on: May 19, 2009, 05:44:28 AM »

Hello,

What is the largest positive value that can be represented using a 16-bit 2's complement representation?

Im sure its wrong tho, any one know the real answer?
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hayabusa
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 « Reply #1 on: May 19, 2009, 09:21:21 AM »

Been a while since I've done this.  I think you're one shy, and the answer is 32767.

16-bit would be 1000000000000000, and flipping the bits would yield 0111111111111111, which is equal to 32767 decimal.

To support my thinking, I found the following:

"For instance, a 16-bit word can represent signed integers in the range −32 768 to + 32 767."

which I took from:

http://openlearn.open.ac.uk/mod/resource/view.php?id=175771

HTH.

(edit - please excuse me if I'm incorrect, and someone tell us otherwise...  been a LONG time since I'd done these, too)
 « Last Edit: May 19, 2009, 09:29:41 AM by Hayabusa0194 » Logged

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ethicalhack3r
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 « Reply #2 on: May 19, 2009, 12:39:53 PM »

I think your right because 0 is a positive number and I completely forgot about it.

Thanks for the help!
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jason
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 « Reply #3 on: May 19, 2009, 05:50:37 PM »

What was the subject matter of the test, out of curiosity?
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ethicalhack3r
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 « Reply #4 on: May 20, 2009, 06:11:14 AM »

Computer System Fundamentals

The whole module was based on the following book:
Fundamentals of Computer Architecture - Mark Burrell (2004)

http://www.amazon.co.uk/Fundamentals-Computer-Architecture-Mark-Burrell/dp/0333998669
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Andrew Waite
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 « Reply #5 on: May 20, 2009, 11:03:12 AM »

Ethicalhack3r,

The whole module was based on the following book:
Fundamentals of Computer Architecture - Mark Burrell (2004)

Just out of interest, was Mark Burrell also one of the module lecturers?
I remember some sleep-inducing lectures from him

Andrew
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ethicalhack3r
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 « Reply #6 on: May 20, 2009, 04:20:08 PM »

He wasnt one of my lecturers but he used to lecture at Northumbria, think he left a couple of years ago maybe?!

I think its the logic gates that get me nodding off...
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Andrew Waite
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 « Reply #7 on: May 21, 2009, 12:59:40 AM »

Must have left after my days then, tbh think the whole module got me sleeping.

Wish I'd paid more attention now I'm playing with shellcode, turns out the low-level stuff is still relevant. Who'd of thought the lecturers would have a better understanding of the industry than the students?
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