History of the Computer – The Bootstrap


In previous articles in the history of the Computer series we discussed machine code, applications, and memories. We also mentioned that many types of memory are volatile, that is, if we remove power, the memory loses it’s data. So how did the data in your computer right now there? Is this like the Big Bang Theory of the universe? Did it just appear? If you have ever had to reload the operating system, as well as all the other programs you use, you know it is not a simple task to get it onto the disk! After that you need to get it into memory – every time you ‘boot’

What is meant by starting !? Old teacher my first computer engineering course my called it “boot binary loader. There is a hint! The term is said to have originated from fictitious tales of a German character you may have heard of, Baron von Munchhausen.

exploits His was serialized in comic strips and the like, along with Dick Tracey etc. One famous story, he rode Cannonball and decide that it was not such a good idea, divide the enemy side go in the opposite direction, to return to his side.

The outrageous story that we’re concerned about here refers to the time when he fell into the swamp, but was able to save himself by pulling himself out of his hair. Newer versions of this story had him lifted its own bootstraps his. This issue “pull yourself up by your own bootstraps devices” was a common one. It meant to get you out of your own problems.

All this does not have much to do with computers, but it describes how they start!

Early digital computers were loaded from paper tape or punch cards, later magnetic tape, and then disk. You may know that before Windows was DOS, which refers to Disk-based operating system.

The mainframe computer is the operating system that acts as an interface between the machine and the user. This OS is variously known as’ Exec ‘(Executive) or “MCP” (Master Control Program) etc. dependent on their computer systems in use. (New employees were surprised to learn that they had to “start the exec every morning’? – A high CEO turnover). This is roughly the Windows or Linux operating system on your computer.

The OS handles all input from users, allocates time slices and prioritizes jobs, manage print jobs, allocates mass storage, etc. When you talk to your computer, it only hears what the OS tells it! The OS can talk to the computer in its own language. So the OS must be capable of loading itself from a disk or tape memory.

To do this, we have a system where a block of data known as a “boot block”, and is located in the very first block of paper tape, or tape, or address 00 on the disk is read into mention the zero forward. This ‘boot command’ is usually a Read instruction from address 00 on device 00.

The data in the boot block, loads the necessary buffer areas to handle I / O data transfer in the ‘reserved’ area of ​​memory etc. ., prepared for communication with the boot device, for example, the disk contains the OS. Having set up all the necessary buffers, the computer reads and executes instructions from 00 onwards. These instructions, just loaded from the disk boot block, finish the setup process.

A final instruction from the boot block read command to the disk to load the rest of the data for the OS. This data is displayed on the boot block data in memory with the proper documentation required to run the system. When the data is loaded OS can start operations.

It will initialize all subsystems, and check what resources are available. It needs to know how much memory, the data is available on the mass storage, what network resources are available , etc. To do this, it may refer to the previous settings, it compares them what you can see now. Also, the ‘clean’ boot check what resources it has and works.