Boot ROM
Today, a boot ROM is a special memory chip which, as ROM ( read-only memory ) , contains the program code required for the start and initialization process - the so-called bootloader - and after pressing the switch-on or reset button of a device, it is transferred from the device's control unit is read out. With these first data and command sequences, for example, the hardware components of a computer are checked for existence and the start parameters assigned to the respective components - for example CPU, graphics card and drives - are transferred during "initialization".
The boot ROM was already used in the early 1960s in the form of diode arrays in the first programmable electronic computing and machine tools. The future-oriented principle was also adopted for the computer. In the first computer systems, apart from magnetic tapes , there was no mass storage device . Initially, manually created punch cards or strips of paper were used as data carriers . Floppy disks and optical data carriers in the form of CD-ROM and DVD-ROM as well as hard disks are PC components developed later.
The program code required at the start had to be loaded into the main memory with a punched tape , later with a boot diskette, which was time-consuming and error-prone. With the introduction of the module principle in computer architecture, a wide variety of special boards (for example "graphics card", "network card", "sound card", modem and others) were developed. To control the individual components, standards - so-called interfaces - and "drivers" were required. This task was also partially taken over by the boot ROMs; the specific parameters of the main board (the so-called chipset ) and the parameters specifically required for the respective control technology of the main board were saved. In addition to the boot ROM, there is also a special memory module for the BIOS on the computer motherboard ; this code is usually stored on an EPROM or Flash ROM and, in contrast to the boot ROM soldered onto the circuit board, can also be used if necessary replaced ( update BIOS ). In single-chip microcontrollers such as the Atmel AVR , which are found in many electronic devices as controls, the boot ROM is already integrated in the microprocessor.
Individual evidence
- ↑ Bo Hanus: The great user book of electronics . Franzis Verlag, Poing (near Munich) 2002, ISBN 3-7723-5436-X , processors and memory modules, p. 184-185 .