Memory, Storage and I/O devices

Question 1

What is the function of the memory unit

Answer 1

It stores binary instructions and data for the microprocessor

Question 2

What must the MPU do to communicate with the memory

Answer 2

▶ Select the chip
▶ Identify the register
▶ Read from or write int the register.

Question 3

Describe the memory unit and give an example

Answer 3

A memory unit is a circuit that can store bits-high or low.
Generally voltage levels or capacitive charge.
A flip flop or a latch is a memory unit

Question 4

How is data written and read in a memory unit

Answer 4

Data is written through input data DIN. The chip is enable through pin EN
The data is read through pin DOUT

Question 5

Describe the Flip-Flop or Latch as a four-bit register

Answer 5

see slide 47

Question 6

Draw two different representations of a 4 X 8 bit register

Answer 6

see slide 48

Question 7

Draw a 4 X 8 register with chip select

Answer 7

see slide 50

Question 8

Illustrate R/W memory model and ROM model

Answer 8

see slide 51

Question 9

Describe memory mapping

Answer 9

A memory map is a pictorial representation in which memory devices are located in the entire range of addresses for each memory device

Question 10

Draw a Address map for 256 register memory

Answer 10

SEE SLIDE 55 AND 53

Question 11

Describe the address map with a diagram showing how 1K (1024x8) memory is mapped. Show all the control signals

Answer 11

No answer

Question 12

Describe Memory word size

Answer 12

Memory devices are available in various word sizes (1,4 and 8) and the size of the memory chip is generally specified in terms of the total number of bits it can store.
For instance a memory chip of size 1024 x 4 has 1024 registers and each register has 4 bits, thus it can store a total of 4096 = 1024x4 bits.

Question 13

Calculate the number of memory chips needed to design 8K byte memory if the available chip size is 1024x1

Answer 13

No answer

Question 14

What are the two types of peripheral devices

Answer 14

There are two different methods by which I/O devices can be identified one uses 8-bit address and the other uses 16-bit address namely.
▶ Peripheral-Mapped I/O (8bit)
▶ Memory mapped I/O (16bit)

Question 15

Describe the Peripheral mapped I/O:

Answer 15

Here MPU use 8 bit address lines to
identify an input or an output device. The MPU can address up to 256 addresses.

Question 16

Describe Memory mapped I/O

Answer 16

Here the MPU uses 16 address lines to identify an I/O device; an I/O is connected as if it is a memory
register.
The MPU uses the same control signal i.e memory read and memory write and instructions as those of the memory.