COS2621 Final Exam Notes - Summary Computer
Organisation and Architecture
Computer Organisation and Architecture (University of South
... [Show More] Africa)
Distributing prohibited | Downloaded by Thanyani Sirumula ([email protected])
lOMoARcPSD|2861495
This study source was downloaded by 100000824368823 from CourseHero.com on 10-05-2022 08:37:37 GMT -05:00
https://www.coursehero.com/file/44707842/cos2621-final-exam-notes-summary-computer-organisation-and-architecturepdf/
Write notes on memory management:
• Main memory is divided into two parts, one part for OS and one part
for the program currently being executed.
• In a multiprogramming system, the user part of memory is subdivided
to accommodate multiple processes.
• The task of subdivision is carried out dynamically by the OS and is
known as memory management
• Effective memory management is vital.
• Memory needs to be allocated efficiently to pack as many processes
into memory as possible.
ExplaiŶ the terŵ ͚gate͛ iŶ a digital logic circuit:
• A gate is a device that implements a simple Boolean or logical function
such as if A and B are true then C is true. They control data flow
Explain 2 ways to make computerised multiplication more efficient:
• 1. Performing a running addition on the partial products rather than
waiting till the end
• 2. Save time on generation of partial products using add and shift
Four reasons peripheral devices aren͛t connected directly to the system bus:
• Wide variety of peripherals with various methods of operation, and
impractical to concorporate the necessary logic within the processor
to control a range of devices
• Data transfer rate is often slower than memory or processor, thus
impractical to use a high-speed bus
• Data transfer rate is sometimes faster, and mismatch would lead to
inefficiencies
• Peripherals often use different data formats and word lengths than
the computer to which they are attached
Five sequences of hardware events occurring when I/O device completes I/O
operation:
1. The device issues an interrupt signal to the processor
2. The processor finishes execution of the current instruction before
responding to the interrupt
3. The processor tests for an interrupt, determines that there is one then
sends an acknowledgement signal to the device that issued the
interrupt allowing the device to remove the Interrupt signal.
4. The processor prepares to transfer control to the interrupt routine. It
saves necessary info (the status if the processor - contained in PSW
register, the location of the next instruction contained in the counter)
5. The processor loads the program counter with the entry location of
the interrupt handler program that will respond to this interrupt.
What Shortcomings of ASCII led to development of Unicode:
• Unicode was invented to supersede ASCII, As ASCII could only support
a limited number of characters, (2^7 due to them being 7-bit), and did
not support multiple languages past English.
• Unicode supports substantially more characters, and supports a much
wider variety of languages. [Show Less]