Computer-Architecture

A collection of the projects done under the computer architecture course of undergrad.

Navigation

• Tools
• Projects
• Contents

Tools

1. Logisim(2.7.1), download EXE (Requires JRE 1.5.0) or JAR (Works for JRE >= 1.5.0). Open .circ files using this.
2. Atmel Studio 7.0 . Download link
3. Proteus Version 8.15. Download link. Open .pdsprj files using this.
4. Extreme burner. Download link. For burning hex files into atmega32 for hardware simulation

Issue with 7400-lib.circ Logisim Library

The originally downloaded 7400-lib.circ had a bug related to the IC-7483. The $C_{out}$ pin was an input pin instead of the desired output pin.This issue was solved using this .circ file. Also some changes were made to the 7400-lib.circ file for the design.

Projects

• Arithmetic Logic Unit : ALU
• Floating Point Adder : FPA
• Microprocessor without Interlocked Pipelined Stages : MIPS

Contents

Folder	ALU	FPA	MIPS
Specification	..	..	..
Report	..	..	..
Logisim Circuit	..	..	..

ALU

Content

• Circuit Design
• Software Simulation
• Usefool Tools
  • Wire Counter
  • Tester (Credit to aaniksahaa for this amazing tester, I modified it to support file output)
• ICs and symbols used

Circuit Design

The original circuit had a bug which were fixed using this file.
Also for the intuitions behind the design check optimization

Software Simulation ALU

Useful Tools

• Wire Counter calculates the number of wires used in a .circ file.

  • Make sure that your.circ file(whose wire is to be counted) and the wireCount.py are in the same directory.
  • Replace the file_path with the name of your.circ and run the .py.
  • An estimate will be given.

• Tester checks whether the truth table generated from the ALU.circ is correct or not.

  • Open the circuit in Logisim
  • Go to the Project tab and click Analyze Circuit
  • A warning dialog box may appear, click OK
  • The truth table is shown.
  • Press Ctrl+A. Copy.
  • Paste the output here in truth_table.txt
  • Most importantly, in the code, change the check_row function's following fragment as per your specifications.

   if(control == 0):
       Y = A + 2**n_bits - 1
   if(control == 1):
       Y = A + 2**n_bits - B - 1
   if(control == 2):
       Y = A + 2**n_bits - 1
   if(control == 3):
       Y = 2**n_bits - A // negation
   if(control == 4):
       Y = A + 2**n_bits - B
   if(control == 5):
       Y = A & B
   if(control == 6):
       Y = A ^ B
   if(control == 7):
       Y = A ^ B

  • Run check_ALU.py
  • For the entire report, check the generated report.txt.

  The followed naming convention:

    Control bits = cs0, cs1, cs2
    A            = A0, A1 etc
    B            = B0, B1 etc
    S            = S0, S1 etc
    Cout         = Cout
    C, V, S and Z are the status flags
  

ICs and symbols used

Here is a list of ICs, symbols and their meanings used in the ALU.

FPA

Software Simulation FPA

MIPS

• Software Simulation
• Asm Compiler
• How to run

Software Simulation MIPS

Logisim

Proteus

How to run

1. Go to the Compiler directory and open a .asm file with the desired mips assembly code.
2. Run the asm_compiler.py.

python asm_compiler.py <input>.asm

3. The following files will be formed.
   intermediate.asm - Asm file with intermediate code for push and pop instructions.
   log.txt - Log file for the resulting hex code of all instructions and any error if found.
   instruction.hex - Hex code for instruction memory for logisim simulation.
   atmega32_instruction.txt - Hex code for instruction memory for atmega32 simulations used in proteus and hardware design.
4. Proteus and hardware simulation
   • Copy the atmega32_instruction.txt.
   • Open the main.c in atmel studio and navigate to the unsigned int instruction[256] array. This is the instruction memory of our mips. Paste the instructions copied as R.H.S of this array.
   • Build the solution and a new hex file will be formed.
     • For hardware simulation, burn this hex file into the atmega32 simulating the instruction memory using extreme burner.
     • For proteus simulation, open the circuit using proteus. Go to the atmega32 with the name Instruction Memory and load the hex file formed into it.
   • Clock is negative edge triggered. Execute next instruction via clock. Also, supports a reset switch for reseting program counter.
5. Logisim simulation
   • Open the circuit in logisim and follow the video to load the instruction.hex into intruction memory.
   demo.vid.compressed.mp4