LANGUAGE OF THE COMPUTER

     LOW LEVEL LANGUAGE 

Low-level language is a language that provides little or no abstraction  from a computer's instruction set architecture. Generally this refers to either machine code or assembly language. 

   MACHINE CODE vs ASSEMBLY LANGUAGE

ASSEMBLY LANGUAGE  

• We  assign names to operand(e.g. add) and operands(e.g..$t0 )
• Branches and jumps use label instead of actual addresses
• Assemblers support many pseudo-instruction 

MACHINE CODE  

• Binary format that can be stored in memory and decode by the cpu

Assembly language -----> (assembler) -----> Translator

      INSTRUCTION SET          

• Instruction set architecture usually define a "family of microprocessor"
• Example: intelx86(IA32),Sun Sparc, Dec Alpha, IBM/360
• Formally defines the interface between a user and a microprocessor 

                   SPIM - MIPS SIMULATOR                       

• SPIM (MIPS spelt backward!) is a MIPS simulator that 

• reads MIPS assembly files and translate to machine language
• execute the machine language instruction
• shows contents of register and memory
• works as a debugger
• provide basic os

MIPS REGISTER CONVENTION

NAME	REGISTER NUMBER	USAGE	PRESERVE ON CALL?
$zero	0	Constant 0(hardware)	n.a.
$at	1	Reserved for assembler	n.a.
$v0 - $v1	2-3	Returned value	No
$a0 - $a3	4-7	Arguments	Yes
$t0 - $t7	8-15	Temporaries	No
$s0 - $s7	16-23	Saved value	Yes
$t8 - $t9	24-25	Temporaries	No
$gp	28	Global pointer	Yes
$sp	29	Stack pointer	Yes
$fp	30	Frame pointer	Yes
$ra	31	Return addr(hardware)	Yes

You can refer this website 
  http://msdn.microsoft.com/en-us/library/ms253512(v=vs.80).aspx

     OPERANDS    

Register operands

• Data stored in register
• Arithmetic instructions use register operand
• Example:    

•         mov     bx, 10          ; Load constant to BX
          add     ax, bx          ; Add BX to AX
          jmp     di              ; Jump to the address in DI

Memory operands

• Main memory use for composite data
• To apply arithmetic operations
• load value from memory into register
• store result from register to memory
• Example : A[12] = h  + A[8]

    
                 1w    $t0,  32($s3)            #load word
                 add   $t0,  $s2,      $t0
                 sw    $t0,  48($s3)             #store word

Immediate operands

• Certain instructions use data from the instruction itself as one (and sometimes two) of the operands.Such an operand is called an immediate operand. The operand may be 32,16 or 8 bit long.

    REGISTER VS MEMORY

• Register are faster to access than memory
• Operating on memory requires loads and store
• Compiler must use register for variable as much as possible    

INTSRUCTION FORMATS  

REGISTER TYPE (R-TYPE)

• This group includes arithmetics and logic with all operands in register,shift instruction and register direct jump instruction

• All R-Type instructions use opcode 000000

op Operation Code

rs Source register specifier

rt Target register specifier

rd Destination register specifier

shamt Shift amount

funct Function field

 

 

 

 IMMEDIATE TYPE(I-TYPE)

• This group includes instruction with an immediate operand,branch instruction ,and load and store instructions

• All opcode except 000000,00001x,0110xx and 0100xx

op Operation Code

rs Source register specifier

rt Target register specifier

immediate Immediate , branch displacement or address displacement

JUMP TYPE(J-TYPE)

• This group consist of two direct jump instructions(j and jal)
• These instructions required a memory address to specify their operand
• J-type instructions use opcode 00001x

op Operation Code

target Target address

 

SOURCES  

• http://courses.cs.washington.edu/courses/cse378/07au/lectures/L5-machinelang.pdf   

•   http://msdn.microsoft.com/en-us/library/ms253512(v=vs.80).aspx
   

• Lecture note language of the computer 1

• Computer Organization And Architecture Lab Companion(Module 16)

Post by: UMMI IZZATI MUSTAPHA