Bits and Bytes

1
A brief overview of software evolution

• Programming Languages

• First Generation Languages (Machine Language)

• We Actually have to do a few things.

First we have to find the operating code, or op
code (by number) to move the data (lets assume
the command is number 28)
Of course, we have know the identifying number
for each of the registers (assume R1 12 R2
13)
Finally, we have to find the op code for
addition (Assume it is 37).
The code I enter might be
28 2 12
28 3 13
(Well, Kind of Its a little more involved)
37 12 13 13
2

• Programming Languages

• First Generation Languages (Machine Language)

• Lets not forget that the computer is just a
  series of light-switches (binary). Therefore we
  need to convert our decimal values to binary

2 000000000000010 (on 16-bits)
Therefore, We would enter the commands
3 000000000000011 (on 16-bits)
12 00001100 (on 8-bits)
13 00001101 (on 8-bits)
28 00011100 (on 8-bits)
37 00100101 (on 8-bits)
00011100 000000000000010 00001100
00011100 000000000000011 00001101
00100101 00001100 00001101 00001101
MITS Altair
3

• Programming Languages

• Second Generation Languages (Assembly c1948)

• The advancement over machine level languages was
  that it was mnemonic (assisting or intended to
  assist the memory)

We did not need to know the specific register
addresses
We did not need to know the op codes
For the previous example, the code we enter might
be
MOV 2 R1
MOV 3 R2
ADD R1 R2 R2

• An Assembler would then transfer the commands
  into a machine level language

4

• Programming Languages

• Third Generation Languages (mid - late 1950s)

• The advancement over assembly level languages was
  that programmers did not need to know either the
  op codes nor the registers used

• Specific locations in RAM were referred to by a
  user defined name

• The compiler or interpreter, as well as the
  operating system, kept track of the specific
  locations

• For the previous example, the code we enter might
  be

X 2 3 (FORTRAN)

• The code would then be rewritten as either an
  assembly language code or directly to a machine
  level language

5

• Programming Languages

• Third Generation Languages (mid late1950s)

• In the above example X is a specific location
  in RAM, although we dont have to know where it
  is

• It is usually referred to as a variable

• Meaning that we can change the contents of the
  location as we wish

• Although it can be a constant

• Meaning that once we set its value, it can not be
  changed

• Either way, the address is assigned by the
  operating system at run time and managed by the
  compiled program (i.e., the machine-level program)

6

• Programming Languages

• Comparison of COBOL and FORTRAN (Hello World)

• COBOL (COmmon Business-Oriented Language)

• Intended to process large amounts of data as a
  batch

• 001 IDENTIFICATION DIVISION.
• 002 PROGRAM-ID. 'HELLO'.
• 003 ENVIRONMENT DIVISION.
• 004 CONFIGURATION SECTION.
• 005 SOURCE-COMPUTER. IBM-360.
• 006 OBJECT-COMPUTER. IBM-360.
• 0065 SPECIAL-NAMES.
• 0066 CONSOLE IS CNSL.
• 007 DATA DIVISION.
• 008 WORKING-STORAGE SECTION.
• 009 77 HELLO-CONST PIC X(12) VALUE 'HELLO,
  WORLD'.
• 075 PROCEDURE DIVISION.
• 090 000-DISPLAY.
• 100 DISPLAY HELLO-CONST UPON CNSL.
• 110 STOP RUN.

• Edsger Dijkstra, winner of the Turing Award
  remarked that "The use of COBOL cripples the
  mind its teaching should, therefore, be regarded
  as a criminal offense."

7

• Programming Languages

• Comparison of COBOL and FORTRAN (Hello World)

• FORTRAN (FORmula TRANslation)

• Intended as a Scientific Language

PROGRAM MAIN PRINT , 'HELLO WORLD'
STOP END

• It is one of the most popular languages in the
  area of high-performance computing and is the
  language used for programs that benchmark and
  rank the world's fastest supercomputers.

8
An Overview of the C/C Programming Languages
9
Overview of the C Programming Language

• Developed in 1978 at Bell Labs by Kernighan
  Ritchie after A B failed

• Associated with UNIX
• Developed on UNIX Systems
• UNIX and its software are written in c
• Intended as general purpose Language
• Basically a primitive language 34 (28
  original) Key words

float
auto
default
sizeof
union
new
break
do
for
register
static
unsigned
case
goto
double
release
struct
void
char
else
if
return
switch
volatile
typedef
const
enum
int
short
continue
extern
long
while
signed
10
Overview of the C Programming Language

• Developed by  Bjarne Sroustrup  at Bell Labs
  during 1983-1985.

• C is an extension of C.

• Prior to 1983, Stroustrup added features to C and
  formed what he called "C with Classes".

• In 1983 the use of classes and object-oriented
  features with the power and efficiency of C. The
  term C was first used in 1983.

• Additional C Reserved Words

and
default
namespace
reinterpret_cast
virtual
and_eq
not
delete
template
wchar_t
asm
not_eq
xor
dynamic_cast
this
xor_eq
bitand
explicit
operator
throw
export
or
true
bitor
catch
false
try
or_eq
40 Additional 74 Total
class
friend
private
typeid
const_cast
inline
protected
typename
public
using
continue
mutable
11
Overview of the C Programming Language
Computer languages rooted in C
Many later languages have borrowed directly or
indirectly from C, including D, Go, Rust, Java, Ja
vaScript, Limbo, LPC, C, Objective-C, Perl, PHP, 
Python, Verilog (hardware description
language),4and Unix's C shell. These languages
have drawn many of theircontrol structures and
other basic features from C. Most of them (with
Python being the most dramatic exception) are
also verysyntactically similar to C in general,
and they tend to combine the recognizable
expression and statement syntax of C with
underlying type systems, data models, and
semantics that can be radically
different. C and Objective-C started as
compilers that generated C code C is
currently nearly a superset of C,10 while Object
ive-C is a strict superset of C.11
http//en.wikipedia.org/wiki/C_(programming_langua
ge)