INF_106_Lab 3_Practice Activity

Software: machine code
● Software - code that runs on the hardware
● CPU implements "machine code" instructions
● Each machine code instruction is extremely simple
○ e.g. add 2 numbers
○ e.g. compare 2 numbers

Software: machine code
The language of the machine code is hardwired into the
design of the CPU
○ it is not something that can be changed
○ Each family of compatible CPUs (e.g. the very popular
Intel x86 family) has its own machine code which is not
compatible with the machine code of other CPU
families.

Lyrics
CPU is capable of performing simple instructions if you load them into RAM. For example addition/subtraction of two numbers, jumping to another instruction. While CPU is performing an instruction the temporary results are stored inside CPU itself in the fastest, smallest memory locations – registers. CPU starts by fetching an instruction from RAM and then executes/performs it. Then again fetches and executes... This is all CPU does. Initially all programs are on hard disk. When user double-clicks a program icon the machine instructions of that program get loaded to RAM where CPU can access them and execute.

What are the instructions?
CPU has list of defined instructions, such as:
● add values
● store values
● copy values
● increment value
● go to command

Example
Signals sent to CPU
(10110000 01100001) (read in hex B0 61)
B0 means “Move a copy of the following value into AL (place in memory)”
Value in AL memory is equal to 61 in hexadecimal

What is assembly language
CPU understands only electrical signals, such as: (10110000 01100001)
But to be understandable to programmers, assembly languages were created.
Assembly languages use words instead of binary commands, as: MOV AL, 61h

Little Man Computer
The Little Man Computer (LMC) is an instructional model of a computer.
The LMC is generally used to teach students, because it models a simple architecture computer - which has all of the basic features of a modern computer.
It can be programmed in machine code or assembly code.

LMC

Set of instructions:

Try it: Little Man Computer
http://robowriter.info/little-man-computer/
http://peterhigginson.co.uk/LMC/
Battle Tank:
http://pddring.github.io/cpu-battle-tank/

Practice
T1: Read two numbers and output their sum and difference
T2: Enter two numbers, and output them in ascending order
T3: Read three numbers and output them in ascending order

Deadline
Laboratory work 3 deadline 07.02.21 at 23.59 pm.