CMIS 310 Exam 2

What does a system bus do?

A shared electrical or optical communication channel connecting the CPU, primary storage, and peripheral devices, allowing devices to exchange information.

What are the four subchannels of the system bus?

Address bus: memory address of a transfer.

Data bus: data bits.

Control bus: commands, responses, status codes, and signals.

Power bus: electrical power and ground.

What does a bus protocol do?

It is the “language” or rules of a bus: defines signal meanings, bit encoding, commands, device access, timing, and error/status information.

error/status information.

What are some common bus protocols?

PCI, PCIe, USB, SATA, and SCSI.

What is an interrupt?

A signal telling the CPU that an event needs attention (e.g., keypress, completed disk read, arriving network packet, or error). The CPU can work on other tasks until a device signals it. An interrupt handler responds, then the prior work resumes.

What is a stack?

reserved memory that saves suspended programs’ machine states; Last-In, First-Out (LIFO), using PUSH and POP

What is a buffer?

Temporary data-in-transit storage between devices/locations.

What is a cache?

Fast storage retaining data to speed future reads/writes to slower storage; reading cache data does not consume it.

What is the difference between L1, L2, and L3?

L1: integrated with each CPU core and fastest.

L2: slower than L1 and dedicated to one core.

L3: shared by multiple cores on one chip.

What is the difference between scaling up and scaling out?

Scaling up adds more processing capacity/resources to one system (e.g., CPU cores or processors). Scaling out adds more machines/nodes in a cluster or grid to distribute work.

What is compression? Why do we do it?

Compression represents data with fewer bits, reducing required storage and transmission. Lossless preserves the exact original; lossy discards some information to gain greater size reduction.

How is resolution measured?

For static images and printers: dots/pixels per inch (DPI/PPI).

For displays: pixel-matrix dimensions (e.g., 1920 × 1080) are more practical.

What is the difference between RGB and CMY? Where is each used?

RGB (red, green, blue) is an additive color used by displays and TVs.

CMY (cyan, magenta, yellow) is a subtractive color used in printing;

CMYK adds separate black ink/toner.

What is the difference between a vector-based and raster/bitmap image?

Raster/bitmap: stored pixel-by-pixel; enlarging it can show pixelation.

Vector: shapes described by lines/angles/lengths; scales without losing geometric sharpness.

What are the differences between CRT, LCD, and LED?

CRT: bulky cathode-ray-tube display, now largely obsolete.

LCD: liquid crystals between polarizing panels.

LED: semiconductor light-emitting devices;

many consumer “LED monitors” are LCD panels with LED backlights (supplemental distinction).

What are common video connector standards?

HDMI, DisplayPort, DVI, and VGA. Confirm against the additional course material.

What are three types of printers? How do they differ?

Impact/dot-matrix: pins strike a ribbon, slow/noisy and lower quality.

Inkjet: puts liquid ink directly on paper, good quality but relatively slow.

Laser: electrical charge attracts toner; usually faster than inkjet.

What are two types of messages in a communications protocol?

Data messages carry information from sender to receiver(s).

Control messages manage communication (e.g., start/stop, select error detection/correction methods).

What three characteristics of a sine wave can be altered, and why do we care?

Frequency (cycles per second, Hz)

amplitude (wave height/energy);

phase (position in cycle).

Modulating these encodes data onto a carrier wave.

What are some differences between analog and digital signals?

Analog signals vary continuously over possible values.

Digital signals use a finite number of discrete values (e.g., binary zero and one).

The lecture characterizes analog as high capacity but higher error rate, and simple binary digital as lower capacity but lower error rate.

What electromagnetic waves carry Wi-Fi?

Radio-frequency (RF) electromagnetic waves.

How do electrical and optical cabling differ?

Electrical cabling (twisted pair/coaxial) carries electrical signals and is susceptible to electromagnetic interference.

Optical fiber carries light, offers high bandwidth and resists EMI.

Single-mode fiber is for longer distances and generally costs more; multimode is less expensive over shorter distances.

What are the pros and cons of wireless communication?

Pros: flexibility and mobility. Cons: interference, shared capacity, lower effective throughput, security/privacy risks, and wired backhaul/infrastructure requirements.

What are the three duplex modes?

Simplex: one-way only.

Half-duplex: either direction, but only one at a time.

Full-duplex: both directions simultaneously.

What is multiplexing?

Combining independent message streams from different sender/receiver pairs for transmission over a shared channel; a multiplexer combines them and a demultiplexer separates them.

What is the difference between synchronous and asynchronous communication?

Synchronous: continuous data streams, coordinated sender and receiver clocks; often transmitted in blocks/packets.

Asynchronous: packets arrive intermittently with silence between transmissions.

What are basic error detection methods?

Parity checking, block checking, and cyclic redundancy checking (CRC).

Each adds redundant information so a receiver can detect mismatches, often leading to retransmission.

What are the OS layers?

Kernel: hardware control, device drivers, and resource allocation.

Service layer: reusable utilities such as file, network, and window management.

Command layer: GUI or CLI tools for interacting with and managing the system.

What is the difference between real and virtual resources?

Real resources physically exist (CPU, RAM).

Virtual resources are resources presented to programs as though dedicated/available, while the OS actually shares and schedules physical resources.

What is a hypervisor?

Software/an OS component that virtualizes complete hardware-resource collections and runs virtual machines (VMs).

What is a process?

A software execution unit that can be running or idle and can be allocated virtual resources. Processes can spawn child processes.

What is a thread?

A smaller executable unit owned by a process. Threads receive CPU time separately but share memory, files, and other resources with their process.

What is virtual memory management?

Memory management that divides processes into fixed-size pages and RAM into same-size page frames. Inactive pages can be moved to a page/swap file on secondary storage to free RAM.

What is a host OS vs. a client OS?

Host OS: runs on the physical machine and manages physical resources.

Client OS: runs inside a VM and manages the virtual resources assigned to that VM.

What are common Linux commands?

ls = list; cd = change directory; pwd = print working directory; mkdir = make directory; cp = copy; mv = move/rename; rm = remove; sudo = execute with elevated permissions.

Who is Linus Torvalds?

creator of the Linux kernel, initially released in 1991. Verify expected specifics with the linked Linux-history video.

Which level of CPU cache is located in a single core?

L1

Primary system bus protocol?

PCIe

Protocol taking over I/O?

USB

Fundamental lie re: keystroke input to CPU

read from memory

Package of CPU register contents

machine state

Location of machine states

stack

Location between CPU and printer

buffer

What must be present within information for it to be compress

pattern

Example of lossy compressed information

image, video, audio, .mp3, .jpeg, etc.

3 colors on monitor/TV in digital pixel

Red, Green, Blue

3 colors for printer

Cyan, Magenta, Yellow

Another name for bitmap

raster

#FF00FF

purple

White pixel on a monitor

#FFFFFF

3 characteristics of a sine wave

frequency, amplitude, phase

2 characteristics modulated in traditional radio broadcasting

frequency, amplitude

Other signal bleeding into yours

noise

Cable type carries signal furthest

fiber optic

Bi-directional communication

full-duplex

Processing of interweaving messages on shared communication path

multiplexing

3 layers of OS from inner to outer

kernel, service, command

Layer for code re-use

service

Name of Android kernel

Linux

Name of iOS kernel

BSD

11111111, 255, FF is all what?

They all represent the same numerical value: 255, which is the maximum unsigned value that can be stored in 8 bits (1 byte)

During a(n) ______ operation, one or more register values are copied to the top of the stack. During a(n) _______ operation, one or more values are copied from the top of the stack to registers.

Push; Pop

The comparative size of a data set before and after data compression is described by the compression _______

Ratio

If data isn’t exactly the same as the original after compressing and decompressing, the compression algorithm is said to be ______. If data is the same as the original after compressing and decompressing, the compression algorithm is said to be ______

Lossy; Lossless

A(n) _______ is a special-purpose processor dedicated to managing cache content.

Cache controller

A(n) _______ is a communication pathway from the CPU to a peripheral device.

I/O channel

A(n) ________ is implemented using main memory, improves file I/O performance, and is controlled by the operating system.

Disk Cache

The _______ transmits a memory address when primary storage is the sending or receiving device

Address bus

The CPU and bus normally view any storage device as a(n) ________, ignoring the device’s physical storage organization.

Linear address space

Part of a device controller’s function is to translate _______ into physical accesses.

Logical accesses

A(n) ________ controller assumes the role of bus master for all transfers between memory and other storage or I/O devices, leaving the CPU free to execute computation and data movement instructions.

DMA (Direct Memory Access)

When a read operation accesses data already contained in the cache, it’s called a(n) _________

Cache hit

The _______ defines the format, content, and timing of data, memory addresses, and control messages sent across the bus.

Bus protocol

In ______ architecture, multiple CPUs and cache memory are embedded on a single chip

Multicore

The term______ describes methods of increasing processing and other com-

puter system power by using larger and more powerful computers.

Scaling up

_______ architecture is a cost-effective approach to computer design when a single computer runs many different applications or services at once.

multicore

Examples of a(n) ______ bus include SATA and SCSI.

Peripheral

A(n) ______ display illuminates a pixel by using excited gas and a colored phosphor.

plasma

_________ speech-recognition programs must be trained to accurately recognize one person's voice

Speaker-dependent

A video display's resolution is described by the units ______

pixels

Commonly used standards for video controller IDLs include ______ and _______.

PostScript; PDF

A(n) ______is 1/72 of an inch and is considered a standard pixel size.

point

A(n) _______ accepts data or commands over a bus and generates output for a video monitor.

video controller

A collection of characters of similar style and appearance is called a(n) ______

font

A(n) ____________ compresses an image by replacing some image components, such as lines and shapes, with equivalent drawing commands

image description language (IDL)

_______ creates an interlocking pattern of colored pixels that fools the eye into thinking a uniform color is being displayed.

Dithering

___________ is a standardized method of encoding notes and instruments for communication with synthesizers and sound cards.

MIDI (Musical Instrument Digital Interface)

Describe the process by which software recognizes keystrokes.

When a key is pressed, the keyboard generates a scan code. The keyboard controller sends the information to the computer, and the operating system uses a device driver to interpret the scan code and determine which key was pressed.

What is a bitmap? How does a bitmap's chromatic resolution affect its size?

Chromatic resolution is the number of bits used to represent each pixel's color. Higher chromatic resolution allows more colors but increases the amount of storage needed.

What is an image description language? What are the advantages of representing images with image description languages?

An image description language (IDL) uses drawing commands to represent images instead of storing every individual pixel.

Advantages include smaller file sizes for certain graphics, easier editing, and the ability to resize images without losing quality

Why does a video controller have its own processor and memory?

A video controller has its own processor and memory to handle graphics processing and store image data.

This reduces the CPU's workload and allows graphics and videos to be displayed more efficiently.

Describe the technologies used to implement flat panel displays. What are their comparative advantages and disadvantages?

• LCD (Liquid Crystal Display): Uses liquid crystals to control light. It consumes less power but can have limited viewing angles.

• LED-backlit LCD: Uses LED backlighting, offering good brightness and energy efficiency.

• OLED (Organic Light-Emitting Diode): Produces its own light, providing better contrast and thinner displays, but can be expensive.

• Plasma: Uses excited gas and phosphors to create images. It provides good color but consumes more power and produces more heat.

How does a laser printer's operation differ from that of a dot matrix printer?

A laser printer uses a laser, electrically charged drum, and toner to produce images on paper.

A dot matrix printer uses small pins that strike an ink ribbon to form characters and images.

Laser printers generally produce higher-quality output and are faster and quieter than dot matrix printers.

Describe the types of optical input devices. For what type of input is each device intended?

Optical input devices use light to capture or read information.

• Optical scanner: Converts printed documents and images into digital form.

• Barcode reader: Reads barcodes on products and labels.

• OCR (Optical Character Recognition): Converts printed text into computer-readable characters.

• OMR (Optical Mark Recognition): Detects marks on forms, surveys, and multiple-choice tests.

• Digital camera: Captures photographs and videos as digital images.

What additional components are added to flat panel displays to enable it to accept touch input?

Flat panel displays use a touch-sensitive layer or sensors to detect contact from a finger or stylus.

A touch controller interprets the signals and determines where the screen was touched.

What are the components of a communication channel?

A communication channel has three main components: a sending device, a transmission medium, and a receiving device. The sender transmits data, the medium carries it, and the receiver accepts it.

What are the components of a communication protocol?

A communication protocol defines rules for exchanging information. Its components include message content, media control, channel organization, and coordination, such as clock synchronization and error handling.

Describe frequency modulation, amplitude modulation, phase-shift modulation, and on-off keying.

• Frequency modulation (FM): Changes the frequency of a carrier wave.

• Amplitude modulation (AM): Changes the amplitude or strength of a carrier wave.

• Phase-shift modulation (PSK): Changes the phase of a carrier wave.

• On-off keying: Represents binary values by turning a signal on or off.

How does multilevel coding increase a channel's effective data transfer rate?

Multilevel coding uses more than two signal states to represent data. This allows multiple bits to be transmitted with each signal change, increasing the effective data transfer rate.

Describe the relationship between bandwidth, data transfer rate, and signal frequency.

Bandwidth is the range of signal frequencies a channel can transmit. Signal frequency measures cycles per second in hertz (Hz). A larger bandwidth generally supports higher data transfer rates and less distortion.