Unit #2-03

Learning Outcome

At the end of this lesson, you will be able to:

• understand the basics of machine code

  • and why NO ONE uses it any more!

Review

• Von Neumann architecture

Lesson

• now that we know the basics of how every computer works, now we need to program it!

• remember, at this point the computer still only does digital logic!

  • a sequence of 1s & 0s

    • some of the digits represent what operation should be done:

      • move 42 to register A

      • add 10 to register B

      • move contents of register A to memory location XXX

    • some of the digits represent data:

      • the number 42

      • the number 10

      • the address that register A should go to

Activity

• watch this video to see who this digital logic is converted into something that a Von Neumann architecture computer can do something useful

  • https://www.youtube.com/watch?v=dXdoim96v5A&list=PLowKtXNTBypGqImE405J2565dvjafglHU&index=36

  • https://www.youtube.com/watch?v=NtAF-WfWyGU

    • yes, people actually programmed with toggle switches initially!

• and this is why NO ONE ever programs machine code any more!

Daily Assignment

• machine code the 8-Bit Breadboard computer

  • remember the 8-Bit Breadboard computer have 16 memory locations for the program

    • 2⁴ = 16 for what instruction

    • 2⁴ = 16 for the data

      • 2⁴ + 2⁴ = 2⁸ → 8-bit computer!

  • see image below, for all of the commands in the end it can do

    • from this video: https://www.youtube.com/watch?v=FCscQGBIL-Y&list=PLowKtXNTBypGqImE405J2565dvjafglHU&index=41

  • using the same instructions (in binary!), write the following computer program

    • use the HLT command to end your program

      • add numbers 5 + 9 and send the result to output

      • subtract numbers 15 - 3 and send the result to output

• now test out your code:

  • use this repo: https://github.com/Mr-Coxall/TEJ4M-8-Bit-Computer-Emulator

    • NOTE: it is a fork from another student's final project

    • python ./cpu.py add.bin 

    • create a xxx.bin file for each of your programs and run them through the emulator

      • prove your program works, or that the emulator has an error!

Extra

• write a program that will start at number 12 and count down by 2, stop at 0

  • not using a loop, sequentially!

8-Bit Computer OP Codes