23278Re: [midatlanticretro] Re: Today is 11111
- Nov 1, 2011
On Nov 1, 2011 2:58 PM, <system@...> wrote:
> 7(dec)+1(dec) is 8(dec)
> 111(bin)+1(bin) is 1000(bin).
> 8 or -8???
Dude, did you get any sleep???
When one specifies a size, in this case 5bit >>and<< signed integers (namely 2's comp), your number range is limited from
-(2^(n-1)) to (2^(n-1))-1
Unless of course, you intend to use doubles(or any multiple) - but then it still applies
> 2's comp is a contrivance and has nothing to do with implementation in
jeesh, we know who failed Digital 101 now do we ;)
Don't tell me, did you actually build an Full Adder >>and<< Subtractor Logic inside your ALU for class ??
Two's Complement is the main reason you don't need extra hardware for Subtractor logic. You simply use Adder Logic only - even in Multipliers/Dividers. And so became the prevailing dominant method -- among several reasons -- over other signed integer notation, such as, Signed Magnitude, One's Comp, etc -- beginning in the early 60's.
Even DEC knew that ;)
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