ASCII vs UNICODE

The issue with ASCII

The problem with 7-bit ASCII character set is that it is only able to represent 128 different characters. An 8-bit system improves this but the real solution is...

UNICODE

• Languages like Japanese, Arabic and Hebrew have a much larger alphabet than English
• UNICODE uses up to four bytes to represent each character meaning that it can represent up to 110,000 different characters

Data Types

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Representing negative numbers

1. Sign and magnitude

• MSB represents the sign. 1 means that the number is negative and 0 for positive

2. Two's complement

<aside> ✅ Allows for binary addition

</aside>

To write in two's complement, write the usual binary number. Then, starting at the right hand side, leave every bit up to and including the first 1 alone, but invert all the bits after this.

Adding and subtracting binary

• Adding is fairly straight-forward
• For subtracting, convert the number to be subtracted into two's complement and then add together.