Untitled Quiz

Computer Architecture CS 320

• Course taught by Dr. Khaled El Helow
• Course offered by Integrated Thebes Institutes, Thebes Higher Institute of Computer & Management Sciences

Lecture 4: MIPS Format

• Focuses on the MIPS instruction format

Review of Binary Numbers

• Computers use binary digits (bits) in base 2 to represent numbers.
• To calculate a number's value in any base, sum each digit multiplied by the corresponding power of the base.

MIPS 32-bit word

• MIPS words are 32 bits long.
• Bits are numbered from right to left (least significant to most significant bit).
• There are 2³² possible combinations of 32-bit values.
• The smallest possible value is 0.
• The largest possible value is 2³² - 1 = 4,294,967,295.
• Overflow occurs for unsigned numbers if the value exceeds 4,294,967,295.

Two's Complement Numbers

• Negate a two's complement binary number by inverting all bits (0s to 1s and 1s to 0s) and adding 1.
• The sum of a number and its inverse is always 11...11 (all 1s).
• This result represents -1, so inverting and adding 1 to any value gives its negative equivalent.
• Negative numbers have a most significant bit (MSB) of 1. Positive numbers have a MSB of 0.
• For a 32-bit number, each bit's value corresponds to a power of 2. The MSB is multiplied by -2³¹, and other bits are multiplied by appropriate powers of 2.

Range of Signed Numbers (Two's Complement)

• Range of n-bit signed numbers in two's complement is -2^n-1 to 2^n-1-1.

Converting Between Binary, Decimal, and Hexadecimal

• Numbers can be converted between binary, decimal, and hexadecimal systems.

MIPS Instruction Formats

• R-format (register-oriented) instructions involve operations involving registers.
• I-format (immediate) instructions allow for constants and addresses within the format itself.
• J-format (jump) instructions contain instructions associated with jumps and branches.

MIPS Fields

• op: opcode, specifying the operation.
• rs, rt: source registers.
• rd: destination register.
• shamt: shift amount (for shift instructions).
• funct: function code, further specifying the operation.

Design Considerations

• Instructions often require more bits than what is immediately available.
• This compromise is a key aspect of MIPS instruction design principles. Concise format with efficient encoding.

Load Word (lw) Instruction

• lw instruction loads data words from memory addresses.
• Addresses are 16 bits which allows access to 2¹⁶ bytes of memory from a specific register.

MIPS Instruction Encoding

• Instructions are encoded according to R-type and I-type formats.

Translating MIPS Assembly Language to Machine Language

• C code can be translated to MIPS assembly and then to machine code (binary).
• The translation involves using the opcode, registers, and addresses.