Computer Memory Basics

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Questions and Answers

What is a key feature of CD-R discs compared to ordinary CDs?

CD-R discs have a premastered foil layer.

CD-R discs can be overwritten.

CD-R discs use a layer of photosensitive dye. (correct)

CD-R discs do not allow new sessions to be created.

Which of the following statements about Blu-ray Discs is correct?

Blu-ray Discs can only be single-layer with a maximum of 25 GB.

Blu-ray Discs are primarily used for low-resolution video playback.

Blu-ray Discs are incapable of supporting 3D video.

Blu-ray Discs require a different drive than standard DVDs for reading. (correct)

What is the theoretical maximum data transfer speed of the fastest DVD drives?

7 MBps

1.38 MBps

16 MBps

12x (432 MBps) (correct)

What distinguishes DVD-R from DVD+R standards?

DVD-R is more compatible with older DVD players. Signup and view all the answers

What advantage do USB drives have over traditional optical discs?

USB drives have larger storage capacities and are easily portable. Signup and view all the answers

What is the primary difference between HDDs and SSDs in terms of data retention?

SSDs use non-volatile memory, allowing data retention without power. Signup and view all the answers

Which factor most significantly affects the performance of Hard Disk Drives (HDDs)?

The RPM at which the platters spin. Signup and view all the answers

What capacity range can HDDs typically be found in?

100 GB to 10 TB Signup and view all the answers

What technology is used in Solid State Drives (SSDs) that differentiates them from traditional HDDs?

Flash memory. Signup and view all the answers

Which of the following interfaces is most commonly used in modern PCs for connecting internal hard disks?

SATA Signup and view all the answers

What is one of the main advantages of using SSDs over HDDs?

Less physical weight and faster data access. Signup and view all the answers

What is the significance of a drive's access time in relation to its performance?

It measures the delay in locating data on the drive. Signup and view all the answers

Which of the following drive types is typically designed for portability?

2.5” HDDs Signup and view all the answers

What is the main purpose of system memory in a computer?

To run applications and manage data quickly Signup and view all the answers

Which of the following statements is true about optical drives?

They can play consumer versions of CDs, DVDs, and BDs. Signup and view all the answers

What characteristic defines volatile memory, such as RAM?

Data is retained only while powered Signup and view all the answers

Which type of memory is used to refresh periodically to preserve information?

Dynamic RAM (DRAM) Signup and view all the answers

What is the effect of insufficient system RAM on a computer's performance?

Virtual memory is used, which is slower Signup and view all the answers

Which vendors are popularly known for supplying RAM?

Kingston and Crucial Signup and view all the answers

What is the consequence of increasing the bus speed in DDR memory technology?

Increased bandwidth for data transfer Signup and view all the answers

Study Notes

System Memory

System memory is essential for running programs and data quickly, functioning as volatile Random Access Memory (RAM).
RAM retains data only while powered; insufficient RAM can slow performance, necessitating virtual memory on disk.
Dynamic RAM (DRAM) stores data as electrical charges and requires periodic refreshing to maintain information.

Synchronous DRAM (SDRAM)

SDRAM synchronizes with the system bus and has a 64-bit data bus, enabling 64 bits of data transfer per clock cycle.
At 66 MHz, SDRAM provides a memory bandwidth of 528 MBps, packaged in DIMMs for desktops and SODIMMs for laptops.

Double Data Rate SDRAM (DDR SDRAM)

DDR SDRAM enhances speed by performing data transfers at both the beginning and end of clock cycles, effectively doubling data output.
Bus speeds increase incrementally through DDR, DDR2, DDR3, and DDR4 without compromising chip reliability.
DDR specifications are not backward-compatible; older modules cannot be reused on newer motherboards.

Mass Storage Devices

Mass storage devices provide non-volatile data storage, maintaining information without power.
Hard Disk Drives (HDDs) magnetically encode data onto spinning platters and come in 3.5" (desktops) and 2.5" (laptops/externals) formats.

HDD Capacity and Performance

HDDs range from 100 GB to 10 TB with performance influenced by spinning speed (RPM)—5400 and 7200 RPM are common, with high-performance drives at 15,000 RPM.
Access speed typically varies, with high-performance drives achieving access times under 4 ms and typical drives around 9 ms.

HDD Interfaces

Standard interfaces for HDDs include EIDE/PATA, SATA, and SCSI, with modern systems primarily using SATA, supporting multiple drives.

External Hard Drives

External HDDs come in enclosures, supporting USB, Firewire, eSATA, or Thunderbolt ports, available in 3.5" and 2.5" formats.

Data Transfer Interface Bandwidth

USB 2: 480 Mbps; USB 3: 5 Gbps; USB 3.1: 10 Gbps; Thunderbolt 2/3: 20 Gbps/40 Gbps respectively, with specific cabling limits.
Network Attached Storage (NAS) systems house multiple HDDs for shared access over networks.

Solid State Drives (SSD)

SSDs utilize non-volatile flash memory technology, offering faster, lighter alternatives to HDDs and available in various capacities, typically under 512 GB.
SSDs can be standalone or hybrid, using a small cache for frequently accessed data from the SSD portion.

Optical Discs and Drives

Optical formats include CDs, DVDs, and Blu-ray Discs (BD), requiring lasers for data reading, adapted for data storage.
CDs hold approximately 700 MB, DVDs can store up to 17 GB, while BDs offer 25 GB (single-layer) and up to 128 GB (quad-layer).

Recordable and Rewritable Optical Discs

CD-Rs use a photosensitive dye for data, allowing one-time writes. CD-RWs permit rewrites but may not function on older players.
DVDs have recordable (+R/-R) and rewritable formats, with dual-layer options for increased capacity.

Blu-ray Discs

BDs are designed for high-definition media, accommodating demands for higher bandwidth and resolution, with capacities up to 100 GB.

Optical Drive Units

Optical drives are generally built into PCs, with USB-connected external drives available, rated by data transfer speeds.
Data transfer rates for optical drives vary; CDs can reach 52x speed, DVDs up to 16x, and BDs start at 36 MBps.

Removable Flash Memory Devices

USB drives (thumb drives) and SD cards are popular flash memory storage options, with capacities typically ranging from 1 to 256 GB.
SD cards come in various factors (Mini, Micro) and are compatible with multi-card readers; high-speed cards can perform up to 312 MBps.

Usage of Flash Memory

Flash memory is widely used in devices like tablets and smartphones, often expandable via specific memory cards, supporting higher data transfer rates.

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Description

This quiz covers the essential concepts of system memory, focusing on its role and significance in computer performance. It highlights the characteristics of Random Access Memory (RAM) and its volatility. You will learn about the importance of having adequate RAM for optimal PC operation.