Classes/Building an 8-Bit CPU from Scratch
 | This project is currently in development and should not be currently considered complete. Contact the project owner for more information. |
| Creator | Andrew Vaughan |
|---|---|
| Date | May 27, 2017 |
| Estimated Time | 16 Weeks |
| Estimated Cost | $75 |
In this class, taught by Andrew Vaughan, you will learn how to build a functional (albeit, simple) 8-Bit CPU from scratch using breadboards and TTL Integrated Circuits. No prior electronics experience is required in the class, as the basics are covered in the first lesson. At the end of the course, you will have built a fully-functional, modular CPU, as well as your own personalized Assembly language, that you can extend indefinitely to create more extensive functionality.
Office hours are held before and after each class. The office hours prior to the class (timing of which will be announced with each class) are intended for members who have missed classes and need to catch up on modules for the upcoming lesson. Office hours after each class will provide a list of advanced topics from the lesson plan, which will only be covered if interest is shown. This time is also available to assist with debugging problems in circuits.
Time and Location
| Instructor: | Andrew Vaughan (Contact information available on user page) |
|---|---|
| Where: | Pumping Station: One Electronics Lab (2nd Floor) |
| When: | TBD |
| Office Hours: | TBD |
| Minimum Class Size: | 2 |
| Maximum Class Size: | 8 |
Prerequisites
There are minimal prerequisites to attend this class. No prior experience in electronics is needed, nor any experience with soldering or computers. It is important that novices attend the first classes, and make use of office hours, to ask questions before continuing on to more advanced topics.
Materials
Components will be group-purchased before each class to ensure proper components are bought, and to keep prices down. As such, the cost of materials can vary, depending on how many people are in class. While some materials are available in the electronics space, such assumptions should be taken with caution. You don't want to miss a class because the component you need isn't available!
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| This section is still under development. Please check back later for more information. |
Components
The following components are required to build the CPU project. No components are "consumed" by this project, as long as it is built on a breadboard; so, if you so choose, you may reuse these components in future projects. A bulk-purchase option is given to students at the beginning of each class, which serves to reduce costs. The average cost, per-student, when bulk-purchasing all-new components is generally about $TBD. Prices last updated May 31, 2017.
| Category | Cost (Individual) |
Cost (Class Rate) |
Quantity | Component | Type | Modules Used |
|---|---|---|---|---|---|---|
| Base | -- | -- | 1 | 22AWG Solid Wire Kit, Various Colors (see below) | All | |
| $38.76 | $38.76 | 14 | Full-Sized (830-Point) Breadboards† | All | ||
| Resistors | $0.80 | $0.18 | 8 | 470Ω Resistor | ¼W, ±5% Tolerance | Clock, RAM, Display |
| $0.90 | $0.20 | 9 | 1kΩ Resistor | ¼W, ±5% Tolerance | Bus | |
| $0.80 | $0.18 | 8 | 10kΩ Resistor | ¼W, ±5% Tolerance | Clock, Display | |
| $0.20 | $0.08 | 2 | 100kΩ Resistor | ¼W, ±5% Tolerance | Bus | |
| $0.10 | $0.04 | 1 | 1MΩ Resistor | ¼W, ±5% Tolerance | Clock | |
| $2.48 | $2.18 | 1 | 1MΩ Potentiometer | ½W | Clock | |
| Capacitors | $0.90 | $0.65 | 6 | 0.01µF Capacitor | Ceramic, ±10% 50V | Clock, RAM, Display |
| $0.36 | $0.27 | 2 | 0.1µF Capacitor | Ceramic, ±10% 50V | Clock | |
| $0.75 | $0.55 | 1 | 1µF Capacitor | Conformal Coated, ±10% 35V | Clock | |
| Integrated Circuits | $1.64 | $1.33 | 4 | LM555CN | Timer | Clock, Display |
| $1.14 | $1.02 | 1 | 74LS00 | Quad NAND Gate | RAM | |
| $3.45 | $3.06 | 5 | 74LS04 | Hex Inverter | Clock, RAM, Controller | |
| $1.26 | $1.11 | 2 | 74LS08 | Quad AND Gate | Clock, Display | |
| $0.59 | $0.59 | 1 | 74LS32 | Quad OR Gate | Clock | |
| $ | $ | 1 | 74LS76 | Dual JK Flip-Flop | Display | |
| $ | $ | 1 | 74LS86 | Quad XOR Gate | ALU | |
| $ | $ | 1 | 74LS138 | 3-to-8 Line Decoder | Controller | |
| $ | $ | 1 | 74LS139 | Dual 2-Line to 4-Line Decoder | Display | |
| $ | $ | 4 | 74LS157 | Quad 2-to-1 Line Data Selector | RAM | |
| $ | $ | 4 | 74LS161 | 4-bit Synchronous Binary Counter | Program Counter, Controller | |
| $ | $ | 7 | 74LS173 | 4-bit D-Type Register | Register, RAM | |
| $ | $ | 2 | 74LS189 | 64-bit Random Access Memory | RAM | |
| $ | $ | 6 | 74LS245 | Octal Bus Transceiver | Register, ALU, Ram, Program Counter | |
| $ | $ | 1 | 74LS273 | Octal D Flip-Flop | Display | |
| $ | $ | 2 | 74LS283 | 4-bit Binary Full Adder | ALU | |
| $ | $ | 4 | 28C16 EEPROM | Display, Controller | ||
| Switches | $ | $ | 2 | Double-Throw Toggle Switch | 8mm, DPDT, Latching | Clock, RAM |
| $ | $ | 2 | Momentary Tactile Switch | 6mm, Normally-Open | Clock, RAM | |
| $ | $ | 1 | 8-Position DIP Switch | RAM | ||
| $ | $ | 1 | 4-Position DIP Switch | RAM | ||
| LEDs | $ | $ | 41 | Red LED | 3mm, 1.8-2.3V, 20mA | Bus, Register, ALU, RAM |
| $ | $ | 20 | Yellow LED | 3mm, 1.8-2.3V, 20mA | Register, RAM, Controller | |
| $ | $ | 11 | Green LED | 3mm, 2.8-3.6v, 20mA | Ram, Program Counter, Controller | |
| $ | $ | 22 | Blue LED | 3mm, 2.8-3.6v, 20mA | Clock, Register, Controller | |
| $ | $ | 4 | 7-Segment Display | Common-Cathode, 10-Pin, 2mm Pin Pitch | Display | |
† For advanced participants familiar with soldering, StripBoard can be used instead to save space and money (about $30 in savings). Do note, however, that soldering and organization of these boards will not be covered in the class, and if chosen by the student, will need to be managed themselves. Using such boards can also make debugging and modification significantly more time-consuming and difficult. If using StripBoard, ensure that the board's pin pitch is the standard breadboard size of 0.1" (2.54mm).
Wire Color Guide
Wire colors are used for the following, so please ensure any kit you buy contains enough of each. Wire may be available in the Electronics Lab, but gauge and color cannot be guaranteed:
| Red | Power, Positive |
|---|---|
| Black | Power, Ground |
| White | Signal, Clock |
| Yellow | Signal, Control Logic |
| Blue | Signal, Module-to-Bus |
| Green | Signal, Other (IC-to-IC, Module-to-Module, etc) |
Recommended Tools
Most of these tools are available in the space. However, we will need to share them within the group, as well as with others who may be working in the space at the time. Especially in the case of hand tools and multimeters, you may wish to provide your own. Given the simplicity of this project, neither high-end nor high-precision tools are required for this project.
Unless specifically marked, it is recommend that you get your own tools for this project to keep pace with the rest of the class:
| Tool | Details |
|---|---|
| Flush Diagonal Cutters | Used to cut wire and trim pins flush to a surface. Very useful for any electronics project. |
| Self-Adjusting Wire Strippers | Used to trim the ends of wire sheathing (which we do a lot). Simpler strippers exist, if you wish to save money. |
| Multimeter with Standard and Alligator-Clip Probes |
Used to measure voltages, amperage, continuity, and generally debug problem circuits. Given the basic nature of this project, a high-precision multimeter is not necessary |
| Oscilloscope | Used to debug and optimize circuits. We will use the Oscilloscopes in the Electronics Lab. |
Authorizations
Please read the rules and responsibilities in the Electronics Area prior to attending. Along with these rules, the following authorizations must be completed to be eligible for this course:
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| This section is still under development. Please check back later for more information. |
Syllabus
Classes are held weekly, and build on top of each other. It is important that all classes are attended, or completing the CPU will be very difficult. Office hours are made available prior to every class to allow persons who miss classes to catch up prior to starting a new lesson.
Prep Session: Electronics Fundamentals
Prior to getting into the course syllabus, an hour-long session will be hosted for anyone who is new to electronics. Nothing needs to be purchased for this class, and there is no maximum for the number of people who may attend. It is not required for someone interested in this prep class to be registered for the following 8-Bit CPU course - it is open to all members every time it is offered.
This course is not required for members already experienced with electronics in order to be successful with the remaining courses in the class.
Topics
By way of introduction into digital electronics, the prep class will dive into certain fundamental knowledge that is necessary for work on any circuit. The following topics will be covered:
- Basic overview of common components and parts, where they are used, and how they work
- Basic overview of how circuits work (the Hydraulic Analogy)
- Alternating-Current (AC) vs. Direct-Current (DC)
- Different methods of powering circuits on a breadboard
- Building our first circuit - let there be light!
- Kerckhoffs's Principle - AKA, how not to light your breadboard on fire
- Introduction to resistors
- Introduction to switches
- The multimeter, measurement, and calculations
- The Mystery Signal™ - learning how to debug a circuit
- Introduction to diodes and transistors
- Introduction to integrated circuits
After the lesson, students will receive an Electronics Cheat Sheet for their reference throughout the rest of the course.
After the Class
Office hours are held for up to an hour after the class concludes. This is an open-forum time period in which questions can be asked and answered. Optionally, students can also choose between these more-advanced topics, if they wish to learn more about the topics from the class' discussion:
- Ideal components vs. reality
- The physics behind how Diodes and Transistors work
- The wide, wide world of components, and choosing the right one for your circuit
- Different types of switches
- Different types of resistors
Week 01 - Implementing Logic with Transistors
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| This section is still under development. Please check back later for more information. |
Week 02 - The CPU Clock Module
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| This section is still under development. Please check back later for more information. |
Week 03 - The 8-Bit Register Modules
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| This section is still under development. Please check back later for more information. |
Week 04 - Designing an ALU
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| This section is still under development. Please check back later for more information. |
Week 05 - The ALU Module
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| This section is still under development. Please check back later for more information. |
Week 06 - The RAM Module
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| This section is still under development. Please check back later for more information. |
Week 07 - Building a Binary Counter
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| This section is still under development. Please check back later for more information. |
Week 08 - The Program Counter Module
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| This section is still under development. Please check back later for more information. |
Week 09 - Designing for 7-Segment Displays
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| This section is still under development. Please check back later for more information. |
Week 10 - Introduction to EEPROM
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| This section is still under development. Please check back later for more information. |
Week 11 - The Display Module
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| This section is still under development. Please check back later for more information. |
Week 12 - Connecting the Modules with a Bus
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| This section is still under development. Please check back later for more information. |
Week 13 - Designing Control Signals
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| This section is still under development. Please check back later for more information. |
Week 14 - Control Logic Module
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| This section is still under development. Please check back later for more information. |
Week 15 - Programming and Deployment
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| This section is still under development. Please check back later for more information. |
Completion
Upon completion, each member of the class will have a modularized, extendable CPU. The CPU can be programmed using an Arduino Programmer, which can be borrowed during the class, or built in one of the after-hours office-hours. Here are some examples what can be done to extend and modify the basic circuitry:
- Create additional circuitry to support more-advanced instructions
- Add more capabilities to the ALU to enable more-powerful processing
- Transition 7400-series integrated circuits to more-advanced functionality to reduce circuit complexity
- Extend the processing capability to 16- or even 32-bit processing
- Add additional input and output capabilities to the system (e.g., serial controllers, USB, disks, multi-line LCDs, etc...)
- Building the modules in an FPGA