NATIONAL OPEN UNIVERSITY OF NIGERIA
14-16 AHMADU BELLO WAY, VICTORIA ISLAND LAGOS
MARCH/APRIL 2016 EXAMINATION
SCHOOL OF SCIENCE AND TECHNOLOGY
COURSE CODE: CIT411
COURSE TITLE: MICROCOMPUERS AND MICROPROCESSORS
Time: 2 HOURS
INSTRUCTION: Answer Question 1 and any other three.
1.
a. Distinguish between Von Neumann and Harvard architectures.
i) 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
ii) A Harvard Architecture has one memory for instructions and a second for data. The name comes from the Harvard Mark 1, an electromechanical computer which pre-dates the stored-program concept of von Neumann.
b. Write a brief note on each of the following:
Assembler:- A program that translates assembly language into machine language.
RISC processor:- The RISC (Reduced Instruction Set Computer) is a processor used in Apple’s PowerPC to introduced a new architecture that increased the speed of the processor because it had been designed to understand a relatively small number of basic instructions.
Multiprocessor:- .
2.
a. Distinguish between machine language and assembly language.
Machine language is the binary form of instructions that a processor can run directly.
Assembly Language:- is a programming language that is very similar to machine language, but uses symbols instead of binary numbers. it contains a short word or "mnemonic"
b. Write a brief note on each of the following:
Assembler directive:- The assembler directives are special instruction to the assembler program to define some specific operations but these directives are not part of the executable program
Subroutine:- A subroutine is called using the LCALL or the ACALL instruction
Instruction:-
3.
a. Briefly describe what Direct Memory Access (DMA) is.
Direct Memory Access, or DMA, is a method of accessing and transferring data stored in a computer's random access memory, or RAM, without having to involve the computer's central processing unit.
b. Distinguish between Instruction Set Architecture and Microarchitecture.
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. WHILE 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
4.
a. Write brief notes on the following:
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.
Program counter:- is a 16-bit register that deals with sequencing the execution of instructions. This register is a memory pointer.
Stack pointer:- The 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.
b. Write down the full interpretation of the following instructions:
MOV R2, #72h:- Move immediate data value 72h to register R2
POP 80h:- The data from current SP address is copied to 80h and SP is decremented.
ADD A, #22h:- Adds the number 22h to A, putting sum in A
INC R7:- Increment register R7
5.
a. Briefly describe what an interrupt is, and explain what happens when it is triggered.
An interrupt can be defined as some event, which interrupts normal program execution or
An interrupt is a signal that causes the computer to alter its normal flow of instruction execution.
When an interrupt is triggered, the following actions are taken automatically by the microcontroller.
i) The current Program Counter is saved on the stack, low-byte first.
ii) Interrupts of the same and lower priority are blocked.
iii) In the case of Timer and External interrupts, the corresponding interrupt flag is cleared.
iv) Program execution transfers to the corresponding interrupt handler vector address.
v) The Interrupt Handler Routine executes.
b. Write brief notes on the following:
Opcode:- Operation Code. The portion of an instruction word that specifies what kind of instruction it is.
Operand:- Operand(s) are internal register and are coded into the instruction.
Mnemonics:- A symbolic representation of an opcode.
Data Bus:- carries data stored in memory (or an I/O device) to the CPU or from the CPU to the memory (or I/O device).
SEPTEMBER/OCTOBER 2015 EXAMINATION
1.
a. Write a brief note on each of the followi ng:
i. VLSI technology
ii. RISC processor (previously answered)
iii. ALU:- The ALU performs the actual numerical and logic operation such as ‘add’, ‘subtract’, ‘AND’, ‘OR’, an so on.
b. D istinguish between Von N eumann and Harvard arch tectures. (previously answered)
2.
a. For a microprocessor briefly describe th e following features:
i. Word‐size:-
ii. Processing speed
iii. Instruction set:- determines what functions the microprocessor can perform.
iv. Memory:- The memory of a microcomputer is an essential part of the system.
b. Distinguish between independent I/O and memory‐mapped I/O.
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:
OCTOBER/NOVEMBER 2014 EXAMINATION
CIT 411 – MICROCOMPUTERS AND MICROPORCESSORS
1. (a) Write out the meaning of these acronyms
i. VLSI:- Very Large Scale Integration
ii. RISC:- Reduced Instruction Set Computer
iii. PIC:- peripheral interface controller
iv. UTLB:- unified (instruction and data) translation look aside buffer
v. MMU:- memory management unit
(b) Using suitable diagram, explain the Von Neumann Architecture.
2. Using suitable diagram, discuss the Harvard Architecture, highlighting the improvement over the
Von Neumann Architecture.
3. Differentiate between the following microprocessor types based on hardware characteristics;
RISC, ISC, VLWI & Superscalar, clearly indicating four of their features each.
Features of the Various Hardware Characteristic
1. Complex Instruction Set Computer (CISC)
1. large number of complex addressing modes
2. many versions of instructions for different operands
3. different execution times for instructions
4. few processor registers
5. microprogrammed control logic
2. Reduced Instruction Set Computer (RISC)
1. one instruction per clock cycle
2. memory accesses by dedicated load/store instructions
3. few addressing modes
4. hard-wired control logic
3. Very Long Instruction Word (VLIW)
1. statically determined instruction-level parallelism (under compiler control)
2. instructions are composed of different machine operations whose execution is started in parallel
3. many parallel functional units
4. large register sets
4. Superscalar Processors
1. ubclass of RISCs or CISCs
2. multiple instruction pipelines for overlapping execution of nstructions
3. parallelism not necessarily exposed to the compiler
4. Explain the principle of operation of DMA, highlighting its benefits.
Direct Memory Access, or DMA, is a method of accessing and transferring data stored in a computer's random access memory, or RAM, without having to involve the computer's central processing unit. This reduces demands on the CPU and allows for greater efficiency in running processes.
Its benefit include:-
Modern computers are able to simultaneously run many processes at once. Without the benefit of direct memory access, the CPU could be tied up a great percentage of time responding to slower peripherals needing access to information stored in memory. A device using one of the several DMA channels that modern computers come with can bypass the CPU. This allows all processes to run faster.
6. Explain the term Interrupt; clearly stating the actions taken by the microcontroller when an
interrupt is triggerred, enumerating at least five registers that the operation is protecting.
Interrupt routine must protect the following registers:
PSW
DPTR (DPH/DPL)
PSW
ACC
B
Registers R0-R7
JUNE/JULY EXAMINATION (2013)
COURSE CODE: CIT 411
COURSE TITLE: MICROCOMPUTERS AND MICROPORCESSORS
TIME ALLOWED:2 HOURS
INSTRUCTION: Answer question one and any other three questions
1. Using suitable diagram, draw the Architectural design of an 8085 Microprocessor, indicating at least
ten of its components and five of its features.
The salient features of 8085 microprocessor are listed below.
• It is 8-bit microprocessor.
• It is manufactured with N-MOS technology.
• It has 16-bit address bus and hence can address up to 216 = 65536 bytes (64KB) memory locations through A0-A15
• The first eight lines of address bus and eight lines of data bus are multiplexed AD0– AD7
• Data bus is a group of eight lines D0– D7
• It supports external interrupt request.
• A 16-bit program counters (PC)
• A 16-bit stack pointer (SP)
• Six 8-bit general purpose register arranged in pairs: BC, DE, HL.
• It requires a signal +5V power supply and operates at 3.2 MHZ single phase clock.
• It is enclosed with 40 pins DIP (Dual in line package). `
3. What is Microcomputer Networking? Outline and discuss any five of its various types.
A computer network consists of several computers that are connected to one another using devices that allow them to communicate.
Its types include
1. Personal Area Networks:-The personal area network, commonly known as a PAN, refers to an individual computer's network of peripherals. Devices that are in immediate access to your computer, such as a printer or IP telephone, are commonly said to exist within a PAN.
2. Local Area Networks:-The local area network (LAN) is designed for working in a small regional space. An example of a LAN is a home with two or more computers connected to a single router. These computers share network resources and can communicate with one another through the connecting device. Wireless access points are an example of a LAN connector, as are hubs and switches. LANs are ideal for fast transfer of data, as the short distance enables above-average data rates.
3. Campus Area Networks:-The campus area network (CAN) is similar to a local area network; however, it contains a great deal more router complexity in order to link buildings and establish different network classifications. A university might deploy a CAN by having an administrative network with access tovimportant records, such as grades and bills, linked across 20 buildings. It could then establish a second class of network over the same 20 buildings for students, requiring different log in policies while disabling access machines containing sensitive information.
4. Metropolitan Area Networks:- A metropolitan area networks, also known as a MAN, links a much larger geographical region than a CAN, LAN or PAM. These networks typically span the entirety of a city and are commonly used by public utilities companies and state services to maintain a private network that covers all regional boundaries.
5. Wide Area Networks:-The wide area network (WAN) is the type of network most users are intimately familiar with. These large networks require complex forwarding and addressing schemes because they must transmit data across wide geographic regions. The most famous WAN is the Internet, requiring vast numbers of routers and switches to forward data based upon Internet Protocol addresses. While these networks are of great benefit to wide-reaching communications, they are typically not as reliable or as fast as smaller networks.
6. (a) What is an Assembly Language. Outlining four of its benefits.
Assembly Language:- is a programming language that is very similar to machine language, but uses symbols instead of binary numbers. it contains a short word or "mnemonic"
Assembly language has several benefits, which are:
Speed: Assembly language programs are generally the fastest programs around.
Space: Assembly language programs are often the smallest.
Capability: You can do things in assembly, which are difficult or impossible in high-level languages.
Knowledge: Your knowledge of assembly language will help you write better programs
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