Hao Cheng

1
Simulator Project
Objective 2
Boot Get_Instr Cpu XPGM Mu
SetMAR 10 functions Fetch
Read Write Display_pgm

• Hao Cheng
• haocheng_at_cs.ucf.edu
• 11-01-05

2
simulator
3
simulator

• Interrupt_handler
• Logon_service
• Get_scripts
• Next_pgm
• Get_memory
• loader
• Dispatch
• Xpgm
• Cpu

editor.dat
4
Get_Instr

• Get_Instr
• read instructions from file into instr_type.
• JUMP 2,0 address
• SKIP 0 count
• SIO 75 burst
• DISK 2000 bytes
• Refer to project_intro.pdf

5
memory

• segment table.
• MEMMAP calloc(2MAXSEGMENTS, sizeof(struct
  segment_type))
• 2 MAXSEGMENTS (defined in config.dat)
• kernel uses upper part
• MEMMAPMAXSEGMENTS 2MAXSEGMENTS 1
• user uses lower part MEMMAP0 MAXSEGMENTS
• memory
• MEM calloc(MEMSIZE, sizeof(struct instr_type))

6
boot

• called from simulator.c
• load kernel boot.dat
• set MEMMAP segment table.
• load code into MEM
• call Display_pgm to write the content of memory
  to file.

7
boot.dat

• format

8
boot

• called from simulator.c
• load kernel boot.dat
• set MEMMAP segment table.
• load code into MEM
• call Display_pgm to write the content of memory
  to file. just refer to correct-output.

9
misc functions

• XPGM context switching
• Mu address translation
• SetMAR memory address register
• Fetch fetch instruction
• Read identical to Fetch
• Write write bytes to memory.

10
Cpu

• set the MAR, set CPU.pc -gt MAR
• fetch instruction from memory
• decode and execute the instruction

11
SIO, WIO, END

• CLOCK current simulation time.
• SIO 75 burst - CPU cycle
• Burst_time from cycle to time
• occurrence time CLOCK burst time
• add_event
• update program counter.
• CPU.pc.offset CPU.pc.offset 2

12
SKIP

• SKIP n count
• if n gt 0, skip the next instruction
• n n 1
• write back to memory call write()
• CPU.pc.offset CPU.pc.offset 2
• Cpu
• if n 0, execute next instruction
• CPU.pc.offset CPU.pc.offset 1
• Cpu
• always followed by JUMP

13
JUMP

• JUMP 2,0 address
• update CPU.pc
• call Cpu().
• unconditional jump
• SKIP JUMP conditional jump

14
Questions?