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The Little Man Computer – Reference

From teachwithict.

 

The little man’s instruction set: These are all the instructions the little man can execute.

 

Instruction

Mnemonic

Machine Code

Load

LDA

5xx

Store

STA

3xx

Add

ADD

1xx

Subtract

SUB

2xx

Input

INP

901

Output

OUT

902

End

HLT

000

Branch if zero

BRZ

7xx

Branch if zero or positive

BRP

8xx

Branch always

BRA

6xx

Data storage

DAT

 

 

 

 

 

 

 

 

 

xx refers to a Mailbox number (Memory Address)

 

 Example (Using Machine Code)

Address

Instruction

What it does:

Mnemonic

Machine Code

00

INP

901

Input a number and put it in the calculator

01

STA 99

399

Store the number in the calculator in memory slot 99

02

INP

901

Input a number and put it in the calculator

03

ADD 99

199

Add the number in memory slot 99 to the number in the calculator

04

OUT

902

Output the number which is now in the calculator

05

HLT

000

Halt