Assembler Tutorial

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Assembler Tutorial

• This program is part of the software suite
• that accompanies the book
• The Digital Core, by Noam Nisan and Shimon
  Schocken
• 2003, www.idc.ac.il/csd, forthcoming by MIT Press
• The software suite was developed by students at
  the
• Efi Arazi School of Computer Science at IDC
• Chief Software Architect Yaron Ukrainitz

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The books software suite

• Translators
• Assembler translates programs written in the
  Hack assembly language to executable code written
  in the Hack machine language
• JcVM (modeled after Javas JVM) translates
  programs written in the stack-based Virtual
  Machine (VM) language to assembly programs
• Jack Compiler translates programs written in the
  Java-like Jack language to VM programs that can
  run on the Virtual Machine.

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The books software suite
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Assembler Tutorial

• Purpose learn how to use the supplied Assembler,
  designed to translate programs from Hack assembly
  to Hack machine code
• Required knowledge Chapter 5 of the book
• Contents
• I. Assembly program example
• II. Command-level Assembler
• III. Interactive Assembler

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Assembler Tutorial
Part I Before we start talking about the
Assembler, lets take a look at a typical
assembly program
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Example
sum.asm
/ sum12 100 / _at_i // i1 M1 _at_sum
// sum0 M0 (loop) _at_i // if i-1000 goto
end DM _at_100 DD-A _at_end Djgt _at_i //
sumi DM _at_sum MDM _at_I //
i MM1 _at_loop // goto loop 0jmp (end)
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Example
sum.asm
/ sum12 100 / _at_i // i1 M1 _at_sum
// sum0 M0 (loop) _at_i // if i-1000 goto
end DM _at_100 DD-A _at_end Djgt _at_i //
sumi DM _at_sum MDM _at_I //
i MM1 _at_loop // goto loop 0jmp (end)

• The assembly program
• Stored in a text file named Prog.asm
• Written and edited in a text editor

• The assembly process
• Translates Prog.asm into Prog.bin
• Comments and white space are ignored
• Variables (e.g. i and sum) are allocated to
  memory
• Labels (e.g. loop and end) are psuedo commands
  that generate no code
• Each assembly command is translated into a 16-bit
  instruction written in the Hack machine language.

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Assembler Tutorial

• Purpose learn how to use the supplied Assembler,
  designed to translate programs from Hack assembly
  to Hack machine code
• Required knowledge Chapter 5 of the book
• Contents
• I. Assembly program example
• II. Command-level Assembler
• III. Interactive Assembler

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Assembler Tutorial
Part II Learn how to use the Assembler from the
operating systems shell level, batch style. (the
Assembler that you have to write should have the
same GUI and behavior)
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The command-level assembler
The OS type command can be used to inspect the
assembly source (.asm file)
(in your computer the path will probably be
different)
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Inspecting the source file
Source code is shown
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Invoking the Assembler
Invoke the Assembler program
Name of the source assembly file (full path).
This file name is an argument of the Assembler
program.
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Invoking the Assembler
The OS type command can be used to inspect the
translated code(.bin file)
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Inspecting the translated code
Binary code is shown
Two ways to test the binary code 1. Invoke the
Hardware Simulator, load the Computer chip, then
load the code (.bin file) into the internal ROM
chip 2. Load and run the code in the CPU
Emulator (much quicker).
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Assembler Tutorial

• Purpose learn how to use the supplied Assembler,
  designed to translate programs from Hack assembly
  to Hack machine code
• Required knowledge Chapter 5 of the book
• Contents
• I. Assembly program example
• II. Command-level Assembler
• III. Interactive Assembler

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Hardware Simulation Tutorial
Part III Learn how to use the interactive
assembler
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Loading an assembly program
1. To load an assembly program, click here.
2. Navigate to a directory and select an .asm
file.
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Loading an assembly program

• Read-only view of the assembly source code
• To edit it, use an external text editor.

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Translating a program
Immediate translation(no animation)
Re-start the translation
Stop the translation
Translate the entire program
Translate line-by-line
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Inspecting the translation
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Saving the translated code
Saves the translated binary code in a .bin file

• If an assembly command contains a syntax error,
  the translation stops with an error message
• The save file operation is enabled only if the
  translation was error-free.

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Comparing the translated code to a compare-file
1. Load a comparison file
2. Select a comparison (.bin) file
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Comparing the translated code to a compare-file
2, Translate the program (any translation mode
can be used, as usual)
1. Comparison file is shown
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Comparing the translated code to a compare-file
The translation of the highlighted line does not
match the corresponding line in the compare file.
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• Mistakes are the portals of discovery
• James Joyce (1882-1941)