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Stage7 - Coggle Diagram

- - - - [Physical page of
        stack x 512] = [Physical Page of code * 512 + 1 ]
- - - - Disables addrs translation
  - - - Process Table Entries
        
        1, pid
        
        4, state
        
        9 . Mode Flag
        
        11, User Page No
        
        12, Kptr
        
        13, UPTR
        
        14 , PTBR
        
        15 , PTLR
    - - Next Instruction to User stack
      - UPTR = SP
      - SP = UserPage*512 -1
        
        KPTR (always be 0 )
      - backup
      - Interrupt
      - Restore
        
        SP = UPTR
        
        ireturn
    - - System Status Table
    - - Stacks during Sys calls
        
        Registers to user Stack
        
        SYs call + 3 Arguments + return value
        
        Push into stack
        
        Invoke INT Sys call
        
        switches to kernel mode
        
        Executes INT 7 (as below )
        
        1 more item...
      - INT 7 (SYS calll 5)
        
        Mode flag in Process Table (sys call)
        
        Usersp = SP
        
        Load File descriptor (-2 for term)
        
        if not -2 return _val = -1
        
        word = ARG2
        
        print word
        
        1 more item...
        
        SP = user Page No x 512 -1
        
        Extract Sys call
      - Stage 11
        
        Expos Specification
        
        Expl Examples
        
        Stage 12
        
        idle
        
        Infinite Loop
        
        PID = 0
        
        state = CREATED
        
        1 more item...
        
        Scheduler
        
        Current PID = [ SYS_TAB + 1 ]
        
        Pt = Pt + 16* CPID
        
        pt + 12 (KPTR) = SP % 512
        
        pt + 14 = PTBR
        
        pt + 15 = PTLR
        
        Toggle CPID (npid)
        
        1 more item...
        
        Os Startup
        
        load idle
        
        IDLE
        
        PTBR -> PAGE_TABLE_BASE
        
        1 more item...
        
        INIT
        
        PAGE_TABLE_BASE + 20
        
        2 more items...
        
        SYS_TAB +1 = PID (RUNNING process)
        
        init
        
        init code
        
        PID =1
        
        state = RUNNING
        
        1 more item...