220-1101 Hardware Study Guide for the CompTIA A+ Core Series Exam

Installing the Appropriate RAM

You must be able to identify and install different RAM types. These questions will be scenario based.

RAM Types

Random access memory (RAM) is the memory bank for data currently in use by a computer or device. RAM memory is temporary. There are numerous types of RAM.

Virtual RAM

Virtual RAM is space on a hard drive that can be allocated when additional memory is requested from an application. This space on the hard drive is also known as a swap file or a paging file.

Small Outline Dual Inline Memory Module (SODIMM)

Small outline dual inline memory modules are commonly found in laptops where space is at a premium and come in 100-, 144-, 200-, 204-, and 260-pin configurations. SODIMM defines the physical form factor of the module.

Double Data Rate 3 (DDR3)

DDR3 is faster than DDR2 and has 30% less power consumption. It comes in 240-pin DIMM and 204-pin SODIMM. Double data rate (DDR), as the name implies, doubles the transfer rate of memory. DDR2 further increases the speed by two. DDR and DDR2 are legacy technologies and no longer used in modern devices.

Double Data Rate 4 (DDR4)

DDR4 is faster than DDR3 and has less power consumption. It comes in 288-pin DIMM and 260-pin SODIMM.

Double Data Rate 5 (DDR5)

DDR5 doubles the speed of DDR4 to 6.4 Gbps with improved power efficiency at 1.1 volts and is available in up to 128 GB modules.

Error-Correcting Code (ECC) RAM

Error-correcting code memory has logic built in to detect and correct single-bit memory errors. For each byte (eight bits) of memory, a parity bit is set that will allow the logic to detect and correct an error in a single bit of each byte. The logic would not correct an error in any byte with more than one bad bit.

Single-Channel

Single-channel memory transfers data in chunks the same size as the system bus’s bandwidth.

Dual-Channel

Dual-channel memory occurs when the memory controller coordinates two memory banks to work in conjunction with one another as a synchronized set when communicating with the CPU, doubling the size of the data transfer.

Triple-Channel

Triple-channel memory coordinates three memory modules for communication with the CPU.

Quad-Channel

Quad-channel memory coordinates four memory modules for communication with the CPU.

Storage Devices

Storage devices are physical components used to store data and files that a computer system needs to operate. You must be able to identify and install different storage devices. Questions about these will be scenario based.

Hard Drives

A hard drive is a non-volatile storage device designed for quick access. It is also known as a hard disk drive (HDD) or a conventional drive and uses a magnetic spinning internal platter to store memory.

Speeds

The speed at which a HDD operates is measured by the number of revolutions per minute (rpm) that the platter of an HDD spins. Higher speeds use more energy and increase heat production. There are four HDD speeds: 5,400 rpm, 7,200 rpm, 10,000 rpm, and 15,000rpm.

Form Factor

The form factor refers to the physical size of the hard drive. Both form factors contain the same connectors.

2.5”—2.5” hard drives are typically used in laptops. 2.5” hard drives can be mounted in a 3.5” form factor slot with the use of a converter kit.

3.5”—3.5” hard drives are typically used in desktop computers.

SSDs

A solid-state drive (SSD) is a flash memory technology that contains no moving parts. Flash memory is a form of nonvolatile read/write memory. Nonvolatile memory retains data when power is removed. Flash erases data in blocks, rather than at the byte level. An SSD uses a series of NAND chips to store memory. SSDs can be made in smaller form factors than HDDs and are capable of much higher speeds.

Communications Interfaces

Communication interfaces are the method through which an SSD communicates with the motherboard and other components.

NVMe—Non-volatile memory express is an open-source standard used to optimize data transfer and can support speeds up to 3.5 GBps.

SATA—The serial AT attachment interface is the slowest of the SSD interfaces.

PCIe—Peripheral component interconnect express offers faster speeds than SATA but slower than NVMe.

Form Factors

Form factors of the SSD are the shape and size of the SSD.

M.2—M.2 is a form factor for SSDs. It is 22 mm wide and can vary in length, with the most common lengths being 80 mm and 60 mm. It is referred to as “gumstick memory” because its size is similar to a stick of gum. M.2 drives plug into an M.2 slot on a motherboard.

mSATA—Mini-serial ATA is a form factor for SSDs. mSATAs have a 30-mm wide, 52-pin connector and use the SATA interface for communication. mSATAs can be either 30 mm x 50.95 mm or 30 mm x 26.8 mm.

Drive Configurations

Storage devices can be configured for high availability so that if one disk in an array of disks fails, data is not lost. The most common configuration is known as redundant array of independent (or inexpensive) disks (RAID).

Redundant Array of Independent/Inexpensive Disks (RAID) 0, 1, 5, 10

There are different RAID configurations, known as RAID 0, 1, 5, 10, that provide different levels of data protection. Striping is a method of storing part of the data on each drive in an array. Mirroring is keeping a full copy of a disk on another disk.

RAID 0: offers striping of data only; no redundancy; good performance

RAID 1: offers mirroring of data only; requires more storage space to store full copies of data

RAID 5: offers striping with parity; minimum of three drives; ability to calculate missing data and rebuild

RAID 10: offers striping and mirroring for full redundancy; minimum of four drives

Removable Storage

Removable storage devices are not contained internally but externally and can be relocated.

Flash Drives

Flash drives are removable storage devices that are capable of containing a large quantity of information in a non-volatile, small, and portable form. Flash memory devices include SD cards, USB flash drives, and optical cards.

Memory Cards

A memory card is a flash memory device that can store data in a non-volatile state. Common memory card form factors include SD, CF, micro-SD, mini-SD, and xD.

Optical Cards

Optical cards are flash storage devices that store data through the use of lasers on spinning discs. Examples of optical cards include CDs, DVDs, and BDs.