Media mistakes

[Black Hole]

Ever had to work with ones-complement arithmetic and the use of negative zero?

I don't know that I've actually worked with it, but yes I know what it is. (Might have done – we were designing with bit-slice ALU implementations)

 

[EEPhil]

Ever had to work with ones-complement arithmetic and the use of negative zero?

Ones-complement sounds familiar, although I can't recall actual usage. Negative zero? If I ever came across it, I've forgotten.

 

[Black Hole]

Negative zero? If I ever came across it, I've forgotten.

Negative values are produced by inverting all the bits, so all-zeros inverts to all-ones.

 

[EEPhil]

Negative values are produced by inverting all the bits, so all-zeros inverts to all-ones.

Makes sense. I really must dig out any old lecture notes I still have (or scanned before disposal) and refresh my memory.

 

[antipodean]

Makes sense. I really must dig out any old lecture notes I still have (or scanned before disposal) and refresh my memory.

This is why most systems work on twos compliment for negative numbers, and on integer systems this means that negative numbers appear to have a greater range than positive numbers, e.g. -256 to +255 for 8 bits.

 

[EEPhil]

This is why most systems work on twos compliment for negative numbers, and on integer systems this means that negative numbers appear to have a greater range than positive numbers, e.g. -256 to +255 for 8 bits.

That I do remember. Along with the fun I can have with incorrectly sized integers in C.

 

[Black Hole]

on integer systems this means that negative numbers appear to have a greater range than positive numbers, e.g. -256 to +255 for 8 bits.

Ahem, that would be 9 bits.

 

[antipodean]

Ahem, that would be 9 bits.

Lets make that -128 to 127 ...