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NOUN Past Questions and Answers - CIT 411 MICROCOMPUTERS AND MICROPROCESSORS MARCH/APRIL 2015 EXAMINATION

NOUN Past Questions and Answers - CIT 411 MICROCOMPUTERS AND MICROPROCESSORS MARCH/APRIL 2015 EXAMINATION

1. (a) Briefly explain the Von Neumann computer architecture.
The von Neumann architecture is a computer design model that uses a processing unit and a single separate storage structure to hold both instructions and data. It is named after Mathematician and early computer scientist John von Neumann.

(b) Outline and discuss the four addressing modes available to an 8085 microprocessor.
Immediate addressing:- Data is present in this instruction. Load the immediate data to the destination provided.

Register addressing:- Data is provided through the registers.

Direct addressing:- it is used to accept data from outside devices to store in the accumulator or send the data stored in the accumulator to the outside device.

Indirect addressing:- This means that the effective address is calculated by the processor. Inaddition, the contents of the address (and the one following) are used to form a second address. The second address is where the data is stored.

2. (a) Explain the term BUS in relation to microcontroller.
A BUS is a collection of wires on which electrical signals pass between components in the system.

(b) Outline and discuss the various subcategories of a computer architecture.
Instruction set architecture, or ISA, is the abstract image of a computing system that is seen by a machine language (or assembly language) programmer, including the instruction set, memory address modes, processor registers, and address and data formats.

Microarchitecture, also known as Computer organization is a lower level, more concrete, description of the system that involves how the constituent parts of the system are interconnected and how they interoperate in order to implement the ISA.

System Design these includes all of the other hardware components within a computing system

3. (a) What are Condition Flags.

CONDITION FLAGS is A register that is treated such that each bit has a different meaning, rather than all of them taken together as a number.

(b) Enumerate and explain at least five components of the 8085 microprocessor.
1. Control Unit Generates signals within uP to carry out the instruction, which has been decoded.
2. Arithmetic Logic Unit :-The ALU performs the actual numerical and logic operation such as
‘ add’, ‘subtract’, ‘AND’, ‘OR’, an so on.
3. Accumulator The accumulator is an 8-bit register that is a part of arithmetic/logic unit (ALU). This register is used to store 8-bit data and to perform arithmetic and logical operations.
The result of an operation is stored in the accumulator. The accumulator is also identified as register A.
4. Program Counter (PC) This 16-bit register deals with sequencing the execution of instructions.
5. Stack Pointer (SP) he stack pointer is also a 16-bit register used as a memory pointer. It
points to a memory location in R/W memory, called the stack.
6. Instruction Register/Decoder:-This is a temporary store for the current instruction of a program. Latest instruction sent here from memory prior to execution. Decoder then takes instruction and ‘decodes’ or interprets the instruction
7. Memory Address Register This component holds address, received from PC, of next program instruction.
8.Control Generator:-This generates signals within uP to carry out the instruction which has
been decoded.
9. Register Selector This block controls the use of the register stack

4. (a) (i) Define the following terms: Opcode and Operand. (previously answered)
(ii) Clearly stating the difference between them.
(b) Write out clearly the following logical operation.
i. SETB 2Fh ; Bit 7 of Internal RAM location 25h is set
ii. CLR C ; Clear the carry flag (flag =0)
iii. CPL 20h ; Complement bit 0 of Internal RAM location 24h
iv. MOV C, 87h ; Move to carry flag the bit 7of Port 0 (SFR at 80h)
v. ANL C,90h ; AND C with the bit 0 of Port 1 (SFR at 90)
vi. ORL C, 91h ; OR C with the bit 1 of Port 1 (SFR at 90)

5. (a) Briefly explain the term Die.
Integrated circuits are miniature complex circuits consisting of semiconductor devices, mainly diodes and transistors, interconnected with various passive elements. All these elements are
formed upon or within a semiconductor, substrate called a die.

(b) Outline and explain at least four technological innovations of microprocessors.
Some of the technological innovations of microprocessors include the following.
1. Digital signal processors (DSPs): A specific new class of microprocessors intended for processing analog signals by sampling their momentary values and using digital processing methods for this
2. Transputers: This is 32-bit microprocessors with a memory and direct links for connection to other transputer units cooperating in a network system.
3. Programmable logic devices (PLDs): complex programmable logic systems consisting of several logic blocks connected via a programmable interconnect matrix.
4. Fifth-generation computers (5G-computers): They have CPU replaced by a problem solving and interference machine (or called interference engine, control structure, rule interpreter) which enables dialogue between a computer and its user.

6. (a) Explain the term Interrupt, listing at least four types of interrupt.
An interrupt is a signal that causes the computer to alter its normal flow of instruction execution. Its types include:- -
I/O interrupt: Generated by an I/O channel or device.
Program interrupt: Generated by some condition that occurs during program execution (eg. divide by zero, illegal machine instruction, etc.)

Timer interrupt: Generated by an internal timer within the CPU
Supervisor call interrupt (SVC): A SVC instruction generates an interrupt that transfers control to an OS service routine. The CPU switches from user mode to supervisor mode.
(b) Outline at least five actions taken by the microcontroller when an interrupt is triggerred, (previosuly answered)

enumerating at least five registers that the operation is protecting.
i. Register Protection:
ii. Forgetting to restore protected values:
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