Skip to content

Latest commit

 

History

History
78 lines (53 loc) · 2.13 KB

README.md

File metadata and controls

78 lines (53 loc) · 2.13 KB
Raw

Pseudo-Assembly

This repository contains a simulator for a ficticious Assembly language used for didactic purposes.

Architecture

The language runs on a virtual machine providing this architecture:

  • An input tape used for reading data from the keyboard
  • An output tape used for writing data on the screen
  • A central memory for storing data
  • A processor with one register called "accumulator"

Instruction set

Each instruction is composed by the opcode plus a parameter (not present in all instructions).

I/O

READ

  • Read an integer value from the input tape and store it in the accumulator.

WRITE

  • Write the integer value stored in the accumulator on the screen.

Memory

LOAD x

  • Load the value stored at memory location x in the accumulator.

STORE x

  • Store a value from the accumulator to memory location x.

Arithmetic

ADD x

SUB x

MULT x

DIV x

  • Perform an arithmetic operation where the first operand is the accumulator, the second operand is the value stored at memory location x and the result is saved in the accumulator.

Branching

BR x

  • Unconditional jump to line x (where 1 is the first line).

BEQ x

BNE x

BL x

BLE x

BG x

BGE x

  • Jump to line x if accumulator is equal to / not equal to / greater than / greater or equal to / less than / less or equal to 0.

Other

END

  • End the program.

Addressing modes

OP x

  • Direct addressing: get the value stored at memory location x.

OP @x or OP@ x

  • Indirect addressing: get the value stored at the address specified in the memory location x.

OP =x or OP= x

  • Explicit addressing: use x as parameter.

Arithmetic and memory instructions can use all of these addressing modes, except STORE =x since it does not make sense.

How to use it

Write the program on a text file and then execute the script pseudo-assembly.py in the Python 3 interpreter giving as command line parameter the created file. For example:

    python pseudo-assembly.py test.asm

The code must be written with one instruction for each line, without line number.