Programmed I/O: In program-controlled I/O, the processor program controls the complete data transfer. So only when an I/O transfer instruction is executed, the transfer could take place. It is required to check that device is ready/not for the data transfer in most cases.  Usually, the transfer is to & from a CPU register & peripheral. Here, CPU constantly monitors the peripheral. Here, until the I/O unit indicates that it is ready for transfer, the CPU wait & stays in a loop. It is time-consuming as it keeps the CPU busy needlessly.

✅ Memory Unit Communication with CPU:

The memory unit which directly communicates with the CPU is known as:

✅ Primary Memory:

Primary memory, also called Main Memory, includes components like RAM (Random Access Memory) and Cache Memory.

✅ Why Primary Memory?

Primary memory is directly accessible by the CPU, allowing it to fetch data and instructions quickly for processing.

✅ Final Answer:

The memory unit that directly communicates with the CPU is: Primary Memory or Main Memory

Time for Fetch & Execute

Definition:
The time required to fetch and execute one machine instruction is called a Machine Cycle / CPU Cycle.

Includes:

• Instruction fetch
• Instruction decode
• Operand fetch (if any)
• Execution
• Result store (if any)

✅ Final Answer: Machine Cycle / CPU Cycle.

Explanation:

CPU performance is determined by factors like:

• Number of cores – Enables parallel processing
• Cache size – Faster data access for the CPU
• Clock speed – Determines how fast instructions are executed

RAM (Random Access Memory) affects overall system performance but does not directly influence the CPU's processing capability. Insufficient RAM may cause swapping (using disk as memory), but it doesn't change the CPU's actual speed.