The IBM POST beep codes are as follows:
★ 1 short beep: This indicates that the POST was normal without any exceptions.
★ 2 short beeps: This indicates there was an error and the message is displayed on the screen.
★ No beep: Indicates no power or disconnection.
★ Continuous beep: This is indicative of a power supply, motherboard or a keyboard problem.
★ One long one short beep: this is indicative of a problem with the mother / system board.
★ One long two short beeps indicates that there is a problem with the display adapter
The modern motherboards at a minimum contain at least:
★ Sockets: The sockets are used to install the processor.
★ The memory slots where the user can install the main memory for the system.
★ Chipset: The chipset is used as a the interface for communication between the processor, main memory and the bus.
★ Flash ROM: These store permanents information such as the BIOS, firmware etc.
★ Power connector: The power connector is connected with the SMPS to deliver power to the components on the motherboard.
★ Expansion slots: The expansion slots are used for various devices to be connected to the system.
The DOS control can be explained in the following steps:
★ The first step the boot loader loads the boot record to the memory, which is given the control ( boot program ) inside the boot record.
★ This program now check for the IO.SYS and MSDOS.SYS as the first entries.
★ Now the program loads the IO.SYS and is given control.
★ The IO.SYS simply loads the MSDOS.SYS file and starts looking for the CONFIG.SYS file .
★ Finally the MSDOS.SYS file is given control, this file now initializes interrupt vectors and loads the COMMAND.COM file.
★ Lastly the autoexec.bat file is loaded, executed.
Characteristics of micro programmed control units:
★ These control units are implemented as micro programs of routines.
★ The control unit implemented in micro program is implemented in the form of a CPU inside another CPU.
★ These types of circuits are simple but comparatively slower.
The characteristics of hardwired control units are as follows:
★ Hardwired control units are based on combinational circuits.
★ In these type of systems the inputs and transforms are set into control signals.
★ Theses units are faster and are known to have a more complex structure.
Some of the purposes for which the LSI are used are as follows:
★ PIC or the programmable interrupt controller.
★ PIT or the programmable interrupt timer.
★ PPI or programmable peripheral interface.
★ CRTC is used for the controlling of the CRT.
★ The floppy disk, hard disk and DMA controller are used for special purposes.
★ The real time calendar or clock is used to organize and sort out things.
★ Multiple programs can be present in the memory at a given time.
★ The resources are dynamically allocated.
★ The size of the memory is larger comparatively.
★ Uni programming allows only one program to be present in memory at a time.
★ The resources are provided to the single program that is present in the memory at that time.
★ Since only one program is loaded the size is small as well.
★ The physical address as the name suggests is the actual location which can be found in the memory.
★ They are used by the CPU in order to specify the range of addresses.