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Prepared by Dhimas Ruswanto. Binary Numbers & Machine Code. Skill Area 311 Part A. Lecture Overview. Binary Numbers Binary Arithmetic ASCII Code Machine Code Instruction Format Advantages and disadvantages of machine code. Binary numbers. What is “Binary”?.
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Prepared by DhimasRuswanto Binary Numbers & Machine Code Skill Area 311 Part A
Lecture Overview • Binary Numbers • Binary Arithmetic • ASCII Code • Machine Code • Instruction Format • Advantages and disadvantages of machine code
What is “Binary”? • A coding system using binary digits 0 and 1 • Represent a letter, digit or other character in a computer or other electronic devices 0 1 OFF ON
You Do The Math When we talk numbers, we use a base-10 system, because we use ten characters to write out all of our numbers. 0 1 2 3 4 5 6 7 8 9 • Computers using binary language operate on a base-2 number system, because the two numbers they use are “0” and “1”. 0 1 Each is a binary digit or “bit” Each bit represents a power of two (22, 23, 24,etc)
Alphabet Our class uses the English language consisting of 26 characters, arranged together in a variety of ways, to communicate. Aa Bb Cc Dd Ee Ff Gg Hh Ii Jj Kk Ll Mm Nn Oo Pp Qq Rr Ss Tt Uu Vv Ww Xx Yy Zz • Computers use binary language consisting of 2 characters, arranged together in groups of eight, to communicate. Aa = 01000001 01100001 Zz = 01011010 01111010 8 bits = 1 byte
Binary Arithmetic • Binary to Decimal(denary):
Binary Arithmetic • Decimal (denary) to Binary: Result =10111 Read from bottom to top
Binary Arithmetic • Decimal Addition • Binary Addition 22 + 23 45 10110 + 10111 101101 • 0 plus 0 produces 0 • 0 plus 1 produces 1 • 1 plus 1 produces 0 with a ‘carry’ of 1 into the next most significant place • 1 plus 1 plus 1 produces 1 with a ‘carry’ of 1 into the next most significant place
Binary Arithmetic • Decimal Multiplication • Binary Multiplication 5 × 3 15 101 × 011 101 101 000 000 001111
Alphanumeric Codes • Beside Numbers, we have to represent other types of information: • Letter of alphabet, mathematical symbols • American Standard Code for Information Interchange (ASCII) - 1968
ASCII Code • Uses 7 bits to encode 128 characters • 7 bits of ASCII Code • (b6 b5 b4 b3 b2 b1 b0)2 • One ASCII character is stored using a byte • One unused bit can be used for other purposes such as representing Greek alphabet, italic type font, etc. • The eighth bit can be used for error-detection
ASCII Code • 128 different characters • 26 + 26 + 10 = 62 (letters and decimal digits) • 32 special printable characters %, *, $ • 34 special control characters (non-printable): BS, CR, etc. • Example: • A 65 = (1000001),…, a 97 = (1100001) • 0 48 = (0110000), …,9 57 = (0111001)
What is a “Machine Code”? • The lowest and most elementary level of Programming Language. • 1st type of PL to be developed. • Represented inside the computer by a String of binary digits (bits) 0 and 1. • The symbol 0 stands for the absence of Electric Pulse and 1 for the presence of an electric pulse.
Why “Machine Code”? • Their order tells the computer what to do. • All other kinds of software need to be translated into machine code before they can be used.
Instruction Format • Each instruction is a number that combines: • An operation code (opcode) that picks a hardware function • One or two input operands(where input comes from) • One output operand (where result goes)
Opcode and operand • An opcode identifies which basic computer operation in the instruction set is to be performed. It tells the computer to do something. • Operands are typically memory or registry addresses. • Opcode is like a verb in a sentence, operands are like the subject in a sentence.
Machine Code Instruction LD, A, number Load A with number. A stands for “accumulator” and LD is short for “load” Opcodes and operands are separated by commas
Advantages of Machine Code • Makes fast and efficient use of the computer • Requires no translator to translate the code i.e. directly understood by the computer
Disadvantages of Machine Code • All operations codes have to be remembered • All memory addresses have to be remembered • It is hard to amend or find errors in a program written in the machine language • These languages are machine dependent
Summary • Binary Numbers: • Binary digits 0 and 1 • 8 bits = 1 byte • ASCII: • 7 bits • 128 characters, 255 with extended • Machine Code • Opcode and operand