Q1.

Computer system need virtual memory because:

i. If computer lacks the random access memory (RAM) needed to run a program or operation, windows uses virtual memory to compensate.

ii. Virtual memory combines computer’s RAM with temporary space on the hard disk. When RAM runs low, virtual memory moves data from RAM to a space called a paging file. Moving data to and from the paging file frees up RAM to complete its work.

Q2.

The digital circuit in a tree-type decoding network with 16 output lines

The first stage is a 2-to-4-line decoder. A new variable is introduced in each successive stage; it or its inverse becomes one input to each of the two-input AND gates in this stage. The second input to each AND gate comes from the preceding stage.

Q3.

The buses line to interface memory

In computer architecture, a bus is a subsystem that transfers data between components inside a computer, or between computers.

System buses are consist of 3 buses line which are:

i. Control Bus -> read memory, write signal, interrupt requestii. Address Bus-> identify the source of data

iii. Data Bus-> carries data

Figure 1

***Figure 1 show how the RAM chips work

Q4.

Interface chip circuit for an 8-word 3-bit RAM chip.

Number of words = 8Word size = 3 bitTotal bits = 8*3 = 24Address line = 8 = 23 , thus 3 lineData line = word size, thus 3 line

Q5.

How CPU read from memory and write to memory

i. The computer loads the operating system (OS) from the hard drive into the system's RAM.

ii. This allows the CPU to have immediate access to the operating system.iii. When something (application)are loaded or opened, it is placed into RAM. This means

that it has been put in the computer's temporary storage area so that the CPU can access that information more easily.

iv. The CPU requests the data it needs from RAM, processes it and writes new data back to RAM in a continuous cycle.(The data shuffling between CPU and RAM)

v. When an application is closed, it and any accompanying files are usually purged (deleted) from RAM to make room for new data. If the changed files are not saved to a permanent storage device before being purged, they are lost.

A2@A1

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