CSE-306-Computer-Architecture-Sessional

This is a repository containing all the simulations and reports of CSE-306 Computer Architecture Sessional.

4 bit ALU

This ALU contains:

• Two 4 bit inputs A and B
• Three select bits S₂, S₁, S₀ as ALU opcodes
• One 4 bit output
• Four flags: Z (Zero), C (Carry), O (Overflow), N (Negative)

Implemented functions and opcodes:

ALU opcodes			Functions
S2	S1	S0 (Cin)
0	0	0	Transfer A
0	0	1	Increment A
0	1	X	AND
1	0	0	Add
1	0	1	Add with carry
1	1	X	OR

Truth table:

ALU opcodes			Required outputs	Adder inputs			Functions
S2	S1	S0 (Cin)		Xi	Yi	Zi
0	0	0	A	Ai	0	Ci	Transfer A
0	0	1	A + 1				Increment A
0	1	0	A ^ B	AiBi	0	0	AND
0	1	1
1	0	0	A + B	Ai	Bi	Ci	Add
1	0	1	A + B + 1				Add with carry
1	1	0	A OR B	AiBi'	Bi	0	OR
1	1	1

Simplified inputs to individual full adders:

X_i = A(S₁' + S₂ XOR B)

Y_i = S₂B

Z_i = S₁'C_i

Circuit diagram:

Floating Point Adder

The adder takes two 32 bit floating point numbers and adds them together. The numbers are represented in the following format:

Sign	Exponent	Fraction
1 bit	10 bits	21 bits (Lowest bits)

The numbers are in normalized form. There are two flags U (underflow) and O (overflow) which are set if the result is too small or too large to be represented in the format.

Flow chart:

Circuit diagram:

What individual components do:

• Sign check: Checks if a 32 floating point number is positive, negative or the exponent is zero. If the number is positive then the output is the same as input. If the number is negative then it outputs the two's complement of the input. And if the exponent is zero then the output is zero.
• Normalizer: Normalizes a floating point number. But if the number is overflowed or underflowed while trying to normalize then the appropriate flags are set.
• Rounder: Rounds the 32 bit significand to 21 bits.

4 bit MIPS processor

How to use:

Write a valid MIPS assembly code and compile the code with MIPS-assembler. Now open the MIPS-simulator with logisim 2.7.1 Then open the machine.txt file (generated after runnig the C++ code) from the instruction memory.

MIPS instruction formats:

• R-type:

Opcode	Src Reg 1	Src Reg 2	Dst Reg
4-bits	4-bits	4-bits	4-bits

• S-type:

Opcode	Src Reg 1	Dst Reg	Shamt
4-bits	4-bits	4-bits	4-bits

• I-type:

Opcode	Src Reg 1	Src Reg 2/Dst Reg	Addr./Immdt
4-bits	4-bits	4-bits	4-bits

• J-type:

Opcode	Target Jump Address		0
4-bits	8-bits		4-bits

Instruction set:

Instruction Opcode	Instruction	MIPS Instruction Format	Instruction Type
0000	sub	R	Arithmetic
0001	ori	I	Logic
0010	bneq	I	Control
0011	addi	I	Arithmetic
0100	beq	I	Control
0101	or	R	Logic
0110	sw	I	Memory
0111	srl	S	Logic
1000	and	R	Logic
1001	andi	I	Logic
1010	lw	I	Memory
1011	add	R	Arithmetic
1100	sll	S	Logic
1101	subi	I	Arithmetic
1110	j	J	Control
1111	nor	R	Logic

Circuit diagram:

Group Members:

• Anup Bhowmik
• Showvik Biswas
• Fardin Anam Aungon
• Kazi Ababil Azam
• Muhammad Ehsanul Kader