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README.TXT
Itai Zilberstein
- To compile the program use command 'make'. I have used a makefile to compile all the source and header files into the executable mykernel
- Comments about functionality are in the source files
- I have provided testfile.txt, which uses script.txt, script1.txt, script2.txt and script3.txt to demonstrate functionality
- Some notes about backing store, PCB, and exec: the programs are stored as files in the backing store labelled PID_x where x is an integer corresponding to when the program is called. This x s the PID and stored in the PCB of the process.
example:
exec s1 s2 s3
exec s4 s5 s1
will store s1 as PID_0, s2 as PID_1, s3 as PID_2, s4 as PID_3, s5 as PID_4 and the second s1 as PID_5
- My exec command is able to handle programs with more than 10 pages of code. It handles this by storing the frame of page n at index n mod 10 in the page table.
- NEW FOR DISKDRIVER;
- My disk uses non-contiguous index allocation:
- it allocates the next free block on disk to a file only when it writes -- all new created files are intially empty
- the next free block is found when the partition is mounted - it is always the first free block from the start of the data region as there is no 'delete'. We then increment the next free block unti lthe end of the partition.
- the block pointers are usde for index allocation, i.e. blockPtr[i] contains the block location on disk of block i of the file
- the meta data region is the first 'data_start' bytes of the file (set to 200, but can easily be enlarged by changing the variable)
- the format of the meta data is: '#blocks,sizeblocks:[fat entry][fat entry]....[fat entry]-----:DATA REGION'
- the writeBlock and readBlock are wrapped by a file system read and write that deals with the overhead
- partitionFS() works so that it will not overwrite/recreate an existing partition -- if a partition exists it is mounted so that its previous data is persistent, not destroyed
example:
mount partition1 5 5
write file [this]
mount partition1 1 1
read file i
print i
--> outputs: this
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Prototype operating system with simulated concurrent CPU, RAM, file system and hard disk
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