Memory Used By BIOS And Device Drivers, Flash ROM

Memory Used By BIOS And Device Drivers

Once the CPU receives an IRQ, it can process the request for hardware services as soon as it can access the instructions that manage the hardware. These instructions are stored in either System BIOS programs or device driver files. During startup, these instructions are put into memory addresses. To retrieve an instruction, the CPU turns to the appropriate memory address to first read the instruction into its internal memory and then to execute it. Sometimes the BIOS programs are copied into RAM because reading from RAM chips is generally faster than reading from ROM chips.

The process of copying programs from ROM to RAM for execution is called shadowing ROM or just shadow RAM. It doesn’t matter whether these programs are executed directly from the ROM chips or RAM; each line of instruction is assigned the same memory address in both places.

Flash ROM

Flash ROM is a type of memory chip that permanently retains programming code without being electrically charged, but can also be overwritten by new code. With Flash ROM, you can upgrade ROM without having to install a new ROM BIOS chip, which is the more difficult and more expensive ROM update procedure.

You can upgrade BIOS in Flash ROM by overwriting existing BIOS code with new BIOS code stored on disk or downloaded from the Internet. As you add new devices to your system, you can continue to easily and inexpensively update ROM BIOS to manage these devices.