Programming Assignment #5 (100 points)

Basic Base/bounds memory management with garbage collection

This exercise is to give you some experience with old fashioned memory management.

Problem specification: You are to mimic process management within physical memory. To do this, you will create an event driven simulation in which a process is "created", memory references for that process are made and processes die. You are to use base and limit registers to make sure that a process stays within bounds and whenever a memory reference is made, you give the EXACT physical address of the location after following the base register. You are to handle external memory fragmentation, by "defragmenting" the physical memory whenever a process wants to start up and there is sufficient memory to support the request.

You may assume there are 10 processes max. You may assume that a process will always ask for at least 2 "words" of memory. A process can ask to start at some time T, it can then make memory reference thereafter, and then it can stop at some other future T. There will also be a directive DUMP, which tells you to state the base and bounds of all ACTIVE processes.
You will output the time step whenever you garbage collect. You can ONLY garbage collect if you do not have contiguous memory to support the new process, but you have enough for the process if you collect the pieces.
You must connect chunks of unused memory without performing garbage collection

The input will start up with a simple configuration line:

RAM 8000

Then the following events are examples of the following input

1 START  P1  2000        -- at time 1,start P1 with size 2000
2 P1 LOC 17              -- at time 2, give the physcial location of P1 VA 17
3 START P2   2000
4 P2 LOC 17
5 START P3   2000
6 P3 LOC 17
7 DUMP                  -- give the base/bounds of all active processes
8 START P4 2000
9 P4 LOC 17
10 STOP P2
11 STOP P3
12 START P5 4000         -- should NOT cause garbage collection
13 P1 LOC 17
14 P4 LOC 17
15 P5 LOC 17
17 STOP                      -- STOP the SIMULATION


A different scenario is

1 START  P1  2000        -- at time 1,start P1 with size 2000
2 P1 LOC 17              -- at time 2, give the physcial location of P1 VA 17
3 START P2   2000
4 P2 LOC 17
5 START P3   2000
6 P3 LOC 17
7 DUMP                  -- give the base/bounds of all active processes
8 START P4 2000
9 P4 LOC 17
10 STOP P1
11 STOP P3
12 START P5 4000         -- WILL cause garbage collection
13 P1 LOC 17
14 P4 LOC 17
15 P5 LOC 17
17 STOP                      -- STOP the SIMULATION