Micro Assembler

LOVELY PROFESSIONAL UNIVERSITY
SYSTEM SOFTWARE

TERM PAPER

TOPIC: MICRO ASSEMBLER
SUBMITTED BY:
SANJAY KUMAR CHAKRAVARTI

ROLL:A10

REG:11006964

SUBJECT CODE: CSE318

SECTION:K2R12

SUBMITTED TO:
MISS. BALWINDER KAUR

DEPT. OF COMPUTER SCIENCES

LPU, PHAGWARA

Acknowledgement

Apart from the efforts of me, the success of this Term paper depends largely on the
encouragement and guidelines of many others. I take this opportunity to express my gratitude to
the people who have been instrumental in the successful completion of this Term Paper.
I would like to show my greatest appreciation to Miss. Balwinder Kaur. I can’t say thank you
enough for his tremendous support and help. I feel motivated and encouraged every time I attend
his meeting. Without his encouragement and guidance this project would not have materialized.
The guidance and support received from all the team members including Shubham Patel,
Raghubendra Singh, who contributed and are contributing to this project, was vital for the
success of the project. I am grateful for their constant support and help.

ABSTRACT
Micro assembler is a sub part of assembler. In this Term paper the focus on Assembler and
Micro Assembler. The working of Micro Assembler its uses in micro Programming, What are the
application of Micro assembler are described. This paper also include the short description of
Micro Assembly Language (MAL). Assembly language is also valuable in reverse engineering,
since many programs are distributed only in machine code form, and machine code is usually
easy to translate into assembly language and carefully examine in this form, but very difficult to
translate into a higher-level language. Tools such as the Interactive Disassembler make
extensive use of disassembly for such a purpose. The micro programmed Data General Eclipse
S/200 computer is available with a writable control store. The WCS feature of the Eclipse is
having extension of the micro programmed control logic of the computer's central processing
unit. It allows a user to implement specialized instructions at a very low level

CONTENTS

TOPIC PAGE NUMBER
1. INTRODUCTION ----------------------------------------------------- 05
2. ASSEMBLY LANGUAGE -------------------------------------------- 06-07
3. ASSEMBLER ----------------------------------------------------------- 07-08
4. MICROASSEMBLER ------------------------------------------------- 08-09
5. MAL ---------------------------------------------------------------------- 10-11
6. APPLICATIONS -------------------------------------------------------- 12
7. BENEFITS ------------------------------------------------------------- 12
8. REFRENCES ------------------------------------------------------------ 13

INTRODUCTION

A micro assembler is a computer program that helps prepare a micro program to control the low
level operation of a computer in much the same way an assembler helps prepare higher level
code for a processor. The difference is that the micro program is usually only developed by the
processor manufacturer and works intimately with the hardware. The micro program defines the
instruction set any normal program (including both application programs and operating
systems) is written in. The use of a micro program allows the manufacturer to fix certain
mistakes, including working around hardware design errors, without modifying the hardware.
Another means of employing micro assembler-generated micro programs is in allowing the same
hardware to run different instruction sets. After it is assembled, the micro program is then loaded
to a store to become part of the logic of a CPU's control unit. Some micro assemblers are more
generalized and are not targeted at single computer architecture. For example, through the use
of macro-assembler-like capabilities, Digital Equipment Corporation used their MICRO 2 micro
assembler for a very wide range of computer architectures and implementations. If a given
computer implementation supports a writeable control store, the micro assembler is usually
provided to customers as a means of writing customized microcode.
Computer programs (software programs) are instructions
for a computer .A computer requires programs to function, typically executing the program's
instructions in a central processor. The program has that the computer can use directly to
execute the instructions. The same program in its human-readable source form, from which
executable programs are derived , enables a programmer to study and develop its algorithms.
Computer source code is often written by professional computer programmers. Source code is
written in a programming language that usually follows one of two main paradigms: imperative
or declarative programming. Source code may be converted into an executable file (sometimes
called an executable program or a binary) by a compiler. Alternatively, computer programs may
be executed by a central processing unit with the aid of an interpreter, or may be embedded
directly into hardware.

ASSEMBLY LANGUAGE

A program written in assembly language it basically contain of a series of instructions-
mnemonics that correspond to a stream of executable instructions, when translated by an
assembler that can be loaded into memory and executed.
For example, anx86/IA-32processor execute the below instruction as given in machine language.
Binary: 10110000 01100001 (Hexadecimal: B0 61)
The mnemonic "move" it tells the opcode1011tomovesthe value in the 2nd operand into the
register. Transforming the assembly language into the machine code is done by an assembler,
and the vice versa by this assembler. In High-level language, there is usually a one to one
relation between simple assembly logics and machine language instructions. But, in few cases,
an assembler provides instructions which will expand into several machine code instructions to
provide its functionality. Each computer structure and processor design has its own machine
understanding language. Each instruction is simple enough to be executed using a relatively
small number of electronic circuits. System may differ by the type of operations they support. For
example, a new 64-bit (AMD processor) machine will have different structure from a 32-bit
(Intel processor) machine. They also have different size structure and the different storage
structure. Multiple collection of mnemonics codes or assembly-language code may exist for a
single instruction set, typically instantiated in different assembler programs. In these cases, the
most popular one is usually that supplied by the manufacturer and used in its documentation.

ASSEMBLER

The advanced assembler creates object code by translating assembly instruction mnemonics into
op codes, and by resolving symbolic names for memory locations and other entities. The use of
symbolic references is only the key feature of assemblers, saving tuff calculations and manual
address. Most assemblers also include macro facilities for performing textual substitution.
To generate common short sequences of instructions to run inline, instead of in a subroutine.
Assemblers are easier to write than compilers for HLL. Advanced assemblers, like RISC based
architectures, such as MIPS, Sun SPARC, and HPPA-RISC, it optimize instruction scheduling to
exploit the CPU pipeline efficiently.
There are two types of assemblers, based upon how many passes through the source are needed
to produce the executable program. One-pass assemblers go through the source code once at a
time and assume that all symbols will be defined before any instruction that references them.
Two-pass assemblers create a table with all unresolved symbols in the first pass, and then use
the 2nd pass to resolve these addresses.
The advantage in the one-pass assemblers is about its speed, which is not as important as it once
was with advances in computer speed and capabilities. The advantage of the two-pass assembler
is that symbols can be defined anywhere in the program source so it's an easier way to
understand the user. Its results to the program can be defined in a more logical and meaningful
way. It will make two-pass assembler programs easier to read and maintain.
More sophisticated high-level assemblers provide language abstractions such as:
Advanced control structures.
High-level procedure declarations and invocations.
High-level abstract data types, including structures, unions, classes, and sets.
Sophisticated macro processing.
Object-Oriented features such as encapsulation, polymorphism, inheritance, interfaces.
Here's how it works:
Most computers come with a specified set of very basic instructions that correspond to the basic
machine operations that the computer can perform. For example, a "Load" instruction causes
the processor to move a string of bits from a location in the processor's memory to a special
holding place called a register.

1.The programmer can write a program using a sequence of these assembler instructions.
2. This sequence of assembler instructions, known as the source code or source program, is then
specified to the assembler program when that program is started.
3. The assembler program takes each program statement in the source program and generates a
corresponding bit stream or pattern.
4. The output of the assembler program is called the object code or object program relative to
the input source program.
5. The object program can then be run whenever desired.
Earlier programmers actually wrote programs in machine code, but assembler languages or
instruction sets were soon developed to speed up programming field. Today, assembler
programming is used only where very efficient control over processor operations is needed. It
requires knowledge of a particular computer's instruction set. Historically, most programs have
been written in "higher-level" languages such as COBOL, FORTRAN, PL/I, and C. These
languages are easier to learn and faster to write programs with than assembler language.

MICROASSEMBLER

A micro assembler also called as meta-assembler. It is a kind of program which helps prepare a
micro program to control the low level operation of a computer in much the same way an
assembler helps prepare higher level code for a processor. The use of a micro program allows
the manufacturer to fix certain mistakes, in hardware design also. Another means of employing
micro assembler-generated micro programs is in allowing the same hardware to run different
instruction sets. When it is assembled, the micro program is then loaded to a control store to
become part of the logic of a CPU's control unit.
Some micro assemblers are more generalized and are not targeted at single computer architecture.
For example, the use of macro-assembler likes capabilities, Digital Equipment Corporation used
their MICRO2 micro assembler for a very wide range of computer architectures.

THE ASSEMBLER USED BY THE MICROSOFT (MASM)

MASM is a Microsoft's assembler and abbreviation used for it is "Macro Assembler." MASM is a
very powerful macro feature, and is capable of writing very low-level syntax, and pseudo-high-

level code with its macro feature. MASM 6.15 is currently available as a free-download from
Microsoft site.
MASM is a one of the Microsoft development tools that are targeted 16-bit, 32-bit and 64-bit
platforms. Versions 6.1 and 6.11 included Phar Lap's TNT DOS extender so that MASM could
run in MS-DOS.
1. MASM will write in Intel Syntax.
2. MASM is used by Microsoft to implement some low-level portions of its Windows
Operating systems.
3. MASM, contrary to popular belief, has been in constant development since 1980, and is
upgraded on a needs-basis.
4. MASM has always been made compatible by Microsoft to the current platform, and
executable file types.
5. MASM currently supports all Intel instruction sets, including SSE2.

MAL (MICRO ASSEMBLY LANGUAGE)

It describes about the lexical, syntactic, and semantic elements of the language, and gives a
focus on microprogramming with the mic1 micro-assembler.

Lexical:

Most assembly language such as Micro-Assembly Language is a line-oriented language. Each
micro-instruction is generally defined on a single line of the program file. The end-of-line is
generally significant. It is a case-sensitive. For example, "AND" is a reserved word
Corresponding to a bitwise operation of the mic1 ALU, while "and" is not reserved and may be
used as a label.

Comments

The comments will begin with two slash characters ("//") and continue to the end of the line.
Blank lines and lines consisting only of white space and comments are ignored by the micro-
assembler.

Directive

Directives for the micro-assembler begin with a period character (".") and may contain
alphabetic characters. There are two micro-assembler directives: ".default" and ".label".
Directives are used to provide guide the behavior of the micro-assembler, and do not correspond
with words in the control store.

Reserved Words

The names of registers and control lines are reserved, as are the words "if", "else", "goto",
"nop", "AND", "OR", and "NOT". For the mic1 architecture, the following words are reserved
and may not be used as statement labels:
MAR
MDR
PC
Fetch
If
Else
goto
nop
AND
OR
NOT

MORE ABOUT THE MICRO ASSEMBLER

Micro Assembler is Integrated Development Environment for assembly programming.
Micro Assembler has a much easier syntax than any of the major assemblers, a great
combination for beginners. Micro Assembler is a Windows based application so you can enjoy
user-friendly Windows environment.

APPLICATIONS

Hard-coded assembly language is typically used in a system's boot ROM(BIOS on IBM-
compatible PC systems). This low-level code is used, among other things, to initialize and test
the system hardware prior to booting the OS, and is stored in ROM. Once a certain level of
hardware initialization has taken place, execution transfers to other code, typically written in
higher level languages; but the code running immediately after power is applied is usually
written in assembly language. The same is true of most boot loaders.
Many compilers render high-level languages into assembly first before fully compiling, allowing
the assembly code to be viewed for debugging and optimization purposes. Relatively low-level
languages, such as C, often provide special syntax to embed assembly language directly in the
source code. Programs using such facilities, such as the Linux kernel, can then construct
abstractions utilizing different assembly language on each hardware platform. The system's
portable code can then utilize these processor-specific components through a uniform interface.
Assembly language is also valuable in reverse engineering, since many programs are distributed
only in machine code form, and machine code is usually easy to translate into assembly
language and carefully examine in this form, but very difficult to translate into a higher-level
language. Tools such as the Interactive Disassembler make extensive use of disassembly for such
a purpose.
A particular niche that makes use of assembly language is the demo scene. Certain competitions
require the contestants to restrict their creations to a very small size (e.g. 256B, 1KB, 4KB or 64
KB), and assembly language is the language of choice to achieve this goal. When resources,
particularly CPU-processing constrained systems, like the earlier Amiga models, and the
Commodore 64, are a concern, assembler coding is a must: optimized assembler code is written
"by hand" and instructions are sequenced manually by the coders in an attempt to minimize the
number of CPU cycles used; the CPU constraints are so great that every CPU cycle counts.
However, using such techniques has enabled systems like the Commodore 64 to produce real-
time3D graphics with advanced effects, a feat which might be considered unlikely or even
impossible for a system with a 0.99MHzprocessor

BENEFITS OF IT:
The micro programmed Data General Eclipse S/200 computer is available with a writable
control store. The WCS feature of the Eclipse is having extension of the micro programmed
control logic of the computer's central processing unit. It allows a user to implement specialized

instructions at a very low level. Its use is however, discouraged since Data General does not
provide software support for the WCS feature.

REFRENCES

http://www.ontko.com/mic1/mal.html#1
http://en.wikipedia.org/wiki/Microassembler
http://findebookee.com/adv.php?q=microassembler%20ppt

Micro Assembler

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