notes.txt

Simulator
==========

Method of Representation
-------------------------

Memory
- Represented by a 2-D char array
- Sizes [256][]

Bus
- Global variable
  int value, current value of bus

**PC MAR OR AR RG will all be objects of the same class**

Program Counter
- Class
-- Members
   int value, current address
-- Functions
   epc(), copies value to bus.value
   lpc(), copies bus.value to values

OR Register
- Class
-- Members
   int value, current value
-- Functions
   eor(), copies value to bus.value
   lor(), copies bus.value to values
   ror(), resets value to zero

AR Register
- Class
-- Members
   int value, current value
-- Functions
   ear(), copies value to bus.value
   lar(), copies bus.value to values
   rar(), resets value to zero

ALU
-Function
- First opr value of bus
- Second opr value of OR
   All individual arithmetic operations of ALU
- After arithmetic functions are called, flagupdate() is called, which updates the flag register.

FL (Flag Register)
- Class
-- Members
   int u,z,nz,p,m,op,ep
-- No functions

MAR
- Class
- Same def as PC, only different in usage

Stack Pointer
- Globally declared stack
- Members of stack
  int value, value
  int address, address of the pointer, starting from 255 down to 0

IR/MS
- Both clubbed together into one class
-- Members
   int ir, base addr of current micro instruction
   int ms, set of micro instructions of current clock cycle

ROM
- Not necessary

Functioning
------------

Upon starting sim, reads .sim which is a settings file

First runs a compiler on the program, checking for syntax errors and missing values.
-Compares each instruction in the program with the list of instruction given.
-Checks for missing flags,movi being followed by a number etc.

Second copies the file into a 2-D char array (RAM).
       Also copies memfile into RAM in correct format.

Third takes each instruction, which is called as a function. Each function will call their micro instructions.
      Depending upon mode, it will print the results after each microins, ins, or after the whole program.
      Depending upon setting, it will print in hex or decimal.