Solutions to FIT1047 week-6 Week-6 topics:
• Discuss CPU, Boot, Motherboard, chipsets and Boot Process:
• Discuss the Assignment -1 progress with the students.
CPU
Exercise 1: What is the difference between the three methods used by the CPU to interact with I/O devices?
SOLUTION
o Polling (busy waiting) – the driver (through the CPU) keeps polling the device to check if it is finished. The frequency of polling is determined by the resolution required for the device, e.g., 1 ms for a mouse.
o Interrupt – the driver asks the device to give an interrupt when finished. The CPU is involved in the data transfer from the device to memory (the OS calls a utility that performs the transfer; this could be as small as one character).
o Direct Memory Access (DMA) – similar to interrupt driven, but enables movement of entire blocks of data. The CPU is involved only in initiating the data transfer, and handling the interrupt at the end of the transfer.
Note: Polling and the other two methods work differently. The difference between interrupt and DMA is more subtle. It pertains mainly to the amount of data that can be transferred without CPU intervention.
Boot Process:
Exercise 2: Difference between the Booting Process with UEFI and the Booting Process with BIOS
The Unified Extensible Firmware Interface (UEFI), like BIOS (Basic Input Output System) is a firmware that runs when the computer is booted. It initializes the hardware and loads the operating system into the memory. However, being the more modern solution and overcoming various limitations of BIOS, Unified Extensible Firmware Interface (UEFI), is all set to replace the former.
Limitations of BIOS
• BIOS is restricted to 1Mbytes of space, can boot from drives of less than 2.2 TB. 3+ TB drives are now standard, and a system with a BIOS can’t boot from them.
• BIOS runs in 16-bit processor mode, and has only 1 MB space to execute.
• It can’t initialize multiple hardware devices at once, thus leading to slow booting process.
Advantages of UEFI over BIOS
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• Overcome Hard Disk Size Limitations: The UEFI firmware can boot from drives of 2.2 TB or larger with the theoretical upper limit being 9.4 Zettabytes ( 1 Zettabyte is about a billion Terabyte)
• Speed and performance: UEFI can run in 32-bit or 64-bit mode, which means your boot process is faster. Provides access to all hardware and faster hardware initialization.
• More User-Friendly Interface: Since UEFI can run in 32-bit and 64-bit mode, it provides better UI configuration that has better graphics and also supports mouse cursor.
• Security: UEFI also provides the feature of Secure Boot. It allows only authentic drivers and services to load at boot time.
• Network: Network access before the O.S has started Exercise 3: Motherboard, chipsets and Boot Process:
a) Explain with respect to the diagram below, what a computer chipset is?
One of the most important device on the motherboard is chipset. A chipset is a smaller set of chips that has replaced a larger number of chips which were found on MB doing different functions. The chipset job is to control data flow between the CPU, Memory, Peripherals, Bus slots and other I/O devices. So all the computer components communicate with the CPU through the chipset. Chipset is consists of Northbridge that is closer to the CPU and
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connected directly to the CPU & MEMORY, AGP & PCI-express slots. The other chip is called the Southbridge is located near the PCI bus slots. The Southbridge connects the PCI slots, IDE connectors, USB, SATA & PATA. They are called the lower portion of the communication. There is no direct connection to the CPU. The CPU can now communicate to these devises via the Northbridge and the Southbridge.
b) Explain how the communication takes place between Northbridge and Southbridge?
Northbridge is faster than the Southbridge, that’s because CPU, RAM and AGP, PCI-e are the most important components of the MB, and need to operate at high speeds possible.
The Southbridge is slower, but it connects PCI bus, SATA and IDE connections and USB ports, they don’t need to be as fast as the other components, so basically the higher speed components are connected to the Northbridge, and slower components are connected to the Southbridge. Both the North and Southbridge make these connections to various parts of the Motherboard using pathways called the BUS. A bus is simply a set of pathways that allow data and signals to travel between components on the MB. A Motherboard bus speed generally refers to the speed of the FSB (front side Bus), the FSB is the connection between the CPU and the Northbridge chipset. However, Intel and AMD optimized this connection and so there is a proprietary connection between the Northbridge and the Southbridge. It’s marked as internal connection in the diagram. Intel’s internal connection is called Direct Media Interface.
Source: http://en.wikipedia.org/wiki/Motherboard#Integrated_peripherals
PART-II Second hour of Lab.
Discuss the Assignment -1 progress with the students.
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