1. Your First Emoji Program
Move a number into the CPU, print it, and stop.
Open this lesson →
1. Predict and trace
Before running the Try program, predict its output and trace the first three executed instructions. Track the relevant registers, flags or memory as needed. Then step the program to compare.
📥 42
🖨️
⏹️
Queue input: None
Initialize memory: All bytes initially zero
2. Build and check
Write a program that prints 42 exactly once and halts. Use LOAD, PRINT, and HALT.
Required instruction types: LOAD, PRINT, HALT
Starter program
# Put 42 in R0, print it, then stop.
HALT
Your program and notes
3. Explain the machine
What is in R0 and output just before PRINT? What PC does HALT leave?
2. Understanding Registers
Use the eight fast workspaces without losing a value.
Open this lesson →
1. Predict and trace
Before running the Try program, predict its output and trace the first three executed instructions. Track the relevant registers, flags or memory as needed. Then step the program to compare.
LOAD 17 R1
LOAD 99
COPY R1 R2
LOAD R2
PRINT
HALT
Queue input: None
Initialize memory: All bytes initially zero
2. Build and check
Keep 17 in R1 and copy it into R2. Print 17, then leave R0 at zero before halting. R1 and R2 must still hold 17.
Required instruction types: COPY, PRINT, HALT
Starter program
LOAD 17 R1
# Copy, print, then clear R0.
HALT
Your program and notes
3. Explain the machine
Why can R0 end at0 while R1 and R2 retain17?
3. Following the Program Counter
Read a trace and separate source lines from instruction addresses.
Open this lesson →
1. Predict and trace
Before running the Try program, predict its output and trace the first three executed instructions. Track the relevant registers, flags or memory as needed. Then step the program to compare.
# A comment is not instruction zero.
LOAD 7
NOP
PRINT
LOAD 9
PRINT
HALT
Queue input: None
Initialize memory: All bytes initially zero
2. Build and check
Print 7 and then 9, in that order, exactly once each. Include a NOP between loading 7 and printing it.
Required instruction types: NOP, LOAD, PRINT, HALT
Starter program
LOAD 7
NOP
# Finish the two outputs.
HALT
Your program and notes
3. Explain the machine
Why do blank/comment source lines not change the output order?