Question 1

POST Behavior: Purpose of the Power-On Memory Test  During PC boot-up, what does the memory test performed by POST primarily accomplish?

Accepted Answer

Introduction / Context: During the Power-On Self-Test (POST), the firmware quickly checks hardware health before handing control to the bootloader. RAM is fundamental; early detection of memory faults prevents unpredictable system behavior later in the boot process. This question asks what the POST memory test is meant to verify. Given Data / Assumptions: Standard PC BIOS/UEFI POST sequence. Memory modules properly seated in supported slots. No overclock or exotic timings unless configured. Concept / Approach: POST performs addressing and pattern tests across the detected address space to confirm that RAM locations can be addressed and store/retrieve data reliably. It also validates that the usable memory space is contiguous and mapped properly, which is essential for OS loaders and memory managers. Step-by-Step Solution: Firmware initializes memory controller settings.Basic write/read patterns are performed to catch stuck bits and addressing errors.Detected capacity is tallied and shown on screen as a count or summary.If failures occur, beep codes or on-screen messages halt the boot for user intervention. Verification / Alternative check: Technicians often follow up with MemTest86+ or similar tools for thorough coverage. Successful extended patterns further validate POST findings. Why Other Options Are Wrong: POST is not superfluous and not an error; it is essential. Merely displaying capacity without testing would miss faults. Therefore, options claiming “ignore” or “only display” are misleading. Common Pitfalls: Assuming a fast boot setting completely replaces testing; some firmwares can reduce or skip extensive tests for speed, but troubleshooting requires full diagnostics when instability is suspected. Final Answer: Checks and verifies that contiguous memory is installed

Question 2

Data Protection Strategy: Safeguarding Files on a Hard Drive  Among common maintenance actions, which one best protects your data against loss from hardware failure, corruption, or accidental deletion?

Accepted Answer

Introduction / Context: Drives can fail suddenly, malware can encrypt files, and user mistakes happen. While maintenance improves performance and health, only a proper copy of your data elsewhere guarantees recovery. This question distinguishes preventative maintenance from true data protection. Given Data / Assumptions: Typical desktop or laptop usage with important documents and media. Potential threats include drive failure, ransomware, and accidental deletion. Access to external drives or cloud services for backups. Concept / Approach: Backups create independent copies of data stored on different media or locations. Even if the original disk is lost or corrupted, the backup can be restored. Defragmentation and file-system checks improve performance and fix metadata errors, but they do not recover lost files after catastrophic failures. Step-by-Step Solution: Define a schedule: daily incremental backups with periodic full backups.Follow the 3-2-1 rule: 3 copies, 2 different media, 1 off-site (or cloud).Automate backup software and regularly test restores.Optionally add versioning and snapshots for rollback from ransomware or mistakes. Verification / Alternative check: Perform a controlled restore test to verify integrity. Monitor backup logs and storage capacity alerts. Why Other Options Are Wrong: Defrag improves file placement; chkdsk/scandisk repair file systems; diagnostics may predict some failures. None guarantees data recovery after loss. Only backups provide that safety net. Common Pitfalls: Keeping the only backup connected (risk of theft/malware), never testing restores, or assuming RAID is a backup (it is not; it improves availability, not history). Final Answer: regular backups

Question 3

Ports and Connectivity: Where Would You Attach a Traditional External Modem?  Identify the appropriate PC interface used by legacy external dial-up modems.

Accepted Answer

Introduction / Context: Before broadband and USB, external dial-up modems connected to a computer using asynchronous serial communication (RS-232). Correctly identifying the proper legacy port helps when supporting older equipment in labs or industry. Given Data / Assumptions: External modem with DB-25 or DB-9 connector. PC equipped with COM ports (serial, asynchronous). Null modem and straight-through cabling considerations apply. Concept / Approach: An external modem interfaces via an asynchronous serial (ASYNC) port, commonly labeled COM1/COM2 and presented as DB-9 or DB-25 connectors. Parallel (LPT) ports are for printers; keyboard and video ports do not carry serial modem signals. Step-by-Step Solution: Locate the PC’s COM port (DB-9 most common on later systems).Use a straight-through serial cable to the modem’s serial interface.Configure baud rate, parity, data bits, and stop bits in the terminal/driver.Verify carrier detect and dial/answer behavior. Verification / Alternative check: Use a loopback plug on the COM port to ensure the port is working, then connect the modem and test with AT commands (e.g., “AT”, “ATI”, “ATDT”). Why Other Options Are Wrong: Parallel port is for printers/legacy devices using different signaling (Centronics/IEEE 1284). Keyboard and video ports are unrelated. “None of the above” is incorrect because the asynchronous serial port is the correct answer. Common Pitfalls: Using a null modem cable instead of a straight-through one for modem connection, or misconfiguring flow control (RTS/CTS vs. XON/XOFF). Final Answer: ASYNC port

Question 4

Power Supply Diagnostics: Measuring AC Ripple on a PC PSU  To check for excessive ripple on a DC output rail of a PC power supply with a multimeter, which measurement mode should be used?

Accepted Answer

Introduction / Context: Switch-mode PC power supplies output regulated DC with some residual AC ripple. Excessive ripple can cause instability, crashes, or component stress. A quick field check can be done with a multimeter; deeper analysis uses an oscilloscope. This question asks for the correct meter setting for ripple measurement. Given Data / Assumptions: Measurement taken across a DC rail (e.g., +12 V, +5 V) and ground. Using a multimeter capable of AC RMS measurement on a DC offset (AC-coupled measurement). Ripple is small compared to the DC level. Concept / Approach: Ripple is the AC component superimposed on a DC output. To measure it with a DMM, select AC voltage mode so the meter filters out (or ignores) the DC component and reports the AC magnitude only. For precise ripple amplitude and frequency content, an oscilloscope is preferred. Step-by-Step Solution: Connect black probe to PSU ground and red probe to the DC rail.Set the multimeter to AC volts to capture the AC component.Compare measured AC RMS value to acceptable ripple limits (vendor spec).If high ripple is observed, inspect capacitors, load, and PSU health. Verification / Alternative check: Use an oscilloscope with AC coupling to view ripple waveform and peak-to-peak amplitude, confirming the DMM reading and revealing switching artifacts. Why Other Options Are Wrong: DC scale measures total including the large DC offset and does not isolate ripple. OHM and Farad scales are not for live-voltage ripple measurement. “None of the above” is incorrect because AC voltage mode is appropriate. Common Pitfalls: Using long ground leads introducing noise, or measuring under no-load conditions that misrepresent in-service ripple. Always measure under realistic load when possible. Final Answer: AC voltage

Question 5

Legacy PC Interrupts: IRQ2 on 16-bit ISA  On the 16-bit ISA bus, IRQ2 is cascaded and effectively mapped to which higher-numbered interrupt line?

Accepted Answer

Introduction / Context: Classic PCs used two cascaded 8259A Programmable Interrupt Controllers (PICs) to expand available hardware interrupts. Understanding the mapping helps interpret device configuration and troubleshoot conflicts in legacy systems. Given Data / Assumptions: System uses dual PICs (master and slave) for IRQ0–IRQ15. Slave PIC is connected to the master via a cascade line. We are considering the standard IBM PC/AT mapping conventions. Concept / Approach: In the PC/AT design, IRQ2 on the master PIC is reserved for cascading to the slave PIC. Devices that would have used IRQ2 are instead serviced through IRQ9, which is tied into the cascade mechanism. Therefore, OS/BIOS typically report such devices as using IRQ9. Step-by-Step Solution: Two 8259A PICs are arranged: master handles IRQ0–IRQ7; slave handles IRQ8–IRQ15.The slave’s interrupt request is wired to the master’s IRQ2 line.Consequently, requests on the slave appear to the CPU through the master as IRQ2, remapped and reported as IRQ9.Hence, devices traditionally associated with IRQ2 are recognized as IRQ9 on AT-class systems. Verification / Alternative check: Review BIOS setup and OS device manager on vintage systems; devices expected on IRQ2 are listed under IRQ9. Technical references for the PC/AT confirm this cascade mapping. Why Other Options Are Wrong: IRQ11, IRQ13, and IRQ15 are separate lines on the slave PIC and not the canonical remap target for IRQ2. “None of the above” is incorrect because 9 is the established mapping. Common Pitfalls: Assuming IRQ2 is freely available on AT-class machines, or forgetting that some adapters labeled “IRQ2/9” simply acknowledge this mapping. Final Answer: 9

Question 6

ESD Safety in PC Repair: Preventing Static Damage  What is the most reliable routine practice to avoid electrostatic discharge (ESD) damage when working inside a PC?

Accepted Answer

Introduction / Context: Electrostatic discharge can silently destroy or weaken sensitive ICs (CPUs, RAM, chipsets, SSD controllers). Effective ESD control is essential during assembly and service. This question identifies the most reliable practice for consistently preventing ESD damage in the field or workshop. Given Data / Assumptions: Technician is opening a PC case and handling components. ESD-safe practices and equipment are available. Grounding points are properly connected to protective earth. Concept / Approach: An ESD wrist strap connected to a known good ground maintains the technician and the system at the same potential, preventing a sudden discharge. While touching ground occasionally helps, it is not continuous or reliable. Footwear or mats may contribute but are not sufficient alone. Denying the risk is dangerous: ESD failures may be latent and appear later as intermittent faults. Step-by-Step Solution: Wear an ESD wrist strap with a 1 MΩ safety resistor in the cord.Clip to the PC chassis or an ESD ground jack connected to earth.Work on an ESD mat tied to the same ground when possible.Handle components by edges; keep them in antistatic packaging until installation. Verification / Alternative check: Use an ESD tester to confirm strap integrity. Monitor field failures: shops enforcing strict ESD procedures report fewer DOA and intermittent returns. Why Other Options Are Wrong: Rubber mats and leather soles do not guarantee equipotential with the PC. Touching ground periodically is inconsistent. Saying ESD does not hurt PCs is false; ESD is a well-documented failure mode. Common Pitfalls: Clipping the strap to painted or insulated surfaces, or forgetting to ground the mat and strap together. Always verify a bare-metal, grounded connection. Final Answer: wear an ESD wrist strap

Question 7

Laser printer preventive maintenance: which component must be routinely vacuumed or replaced to maintain safe, reliable operation? (Assume a standard office laser printer with ozone/air filtration and a user-replaceable toner cartridge.)

Accepted Answer

Introduction / Context: Preventive maintenance for laser printers focuses on air quality, image quality, and mechanical longevity. A key safety concern is the small amount of ozone some models generate around the corona assembly or charging systems. The question asks which component must be vacuumed or replaced as part of routine maintenance. Given Data / Assumptions: Typical office laser printer with electro-photographic process. Contains a corona/charging system and an ozone (or general air) filter. User-replaceable toner cartridge and an optical system with a scanning mirror. Concept / Approach: Corona charging can generate ozone. Manufacturers include an ozone or air filter to trap byproducts and toner dust. Over time, this filter saturates and must be vacuumed or replaced to maintain airflow and reduce odors/irritants. The scanning mirror is a precision optical component—touching or vacuuming it risks misalignment and scratches. The toner cartridge is replaced when low or defective, but it is not a must-change item at every preventative interval unless the service schedule specifies it due to page count. Step-by-Step Solution: Identify required maintenance items in the service manual.Locate the ozone/air filter; remove, vacuum with ESD-safe tool, or replace.Do not touch the scanning mirror or polygon motor; clean only with approved optics methods when explicitly required.Inspect toner cartridge; replace only if end-of-life or poor print quality is diagnosed. Verification / Alternative check: Service logs typically show improved airflow and reduced odors after filter service. Many vendors specify a page-count interval for filter replacement independent of toner levels. Why Other Options Are Wrong: Scanning mirror: Not a routine vacuum/replace item; mishandling can damage optics. Toner cartridge: Replace on wear/low-toner, not universally every PM cycle. All of the above / None of the above: Over-broad or incorrect; only the filter is a must-service item. Common Pitfalls: Vacuuming internal optics with an ordinary vacuum (ESD risk) or touching the mirror with fingers or cloths, which can scratch coatings and cause print artifacts. Final Answer: Ozone filter

Question 8

Internal SCSI setup: when adding a second SCSI hard disk, where should the second drive be connected on the bus?

Accepted Answer

Introduction / Context: SCSI (Small Computer System Interface) devices are attached in a daisy-chain topology. Understanding physical connections and termination is essential for stable operation and proper device detection. Given Data / Assumptions: Two internal SCSI hard disks are being attached. A host adapter (controller) already exists in the system. Standard internal ribbon with multiple 50-pin/68-pin connectors depending on SCSI type. Concept / Approach: SCSI devices share a common bus. Internal devices chain together via available SCSI connectors on the cable or on the drive. Each device requires a unique SCSI ID, and the bus must be terminated at both physical ends (not in the middle). Thus, adding a second drive typically means connecting it to an available SCSI connector on the cable or to an open pass-through connector on the first drive (depending on hardware), keeping the daisy-chain intact. Step-by-Step Solution: Connect the second drive to an open SCSI port on the first hard drive or to the next connector on the internal SCSI ribbon.Assign a unique SCSI ID different from the first drive and the host adapter.Ensure termination occurs only at the two physical ends of the bus.Secure cabling and verify with SCSI BIOS scan. Verification / Alternative check: Run the SCSI utility at boot to confirm both devices enumerate correctly with distinct IDs and proper termination detected. Why Other Options Are Wrong: Any open SCSI port on the computer: Internal chains use the internal bus, not miscellaneous external ports. Serial or parallel ports: Not part of SCSI bus; incompatible electrically and logically. None of the above: The daisy-chain connection is correct. Common Pitfalls: Duplicate SCSI IDs, enabling termination on a middle device, or mixing cable types that do not match signaling standards (SE/LVD). Final Answer: An open SCSI port on the first hard drive

Question 9

Legacy DOS memory manager: what is the primary function of the device driver HIMEM.SYS?

Accepted Answer

Introduction / Context: HIMEM.SYS is a classic MS-DOS and early Windows component that enabled systems to utilize extended memory beyond the 1 MB real-mode boundary. Knowing what it actually manages helps distinguish extended memory (XMS) from expanded memory (EMS) and other device drivers. Given Data / Assumptions: DOS-era PC with CONFIG.SYS loading HIMEM.SYS. 386 or later CPU may also use EMM managers for EMS, but that is separate. ANSI.SYS and display code pages are unrelated drivers. Concept / Approach: HIMEM.SYS implements the XMS (Extended Memory Specification), controls access to memory above 1 MB, and enables use of the High Memory Area (HMA). It is not an ANSI terminal driver, not a code-page driver, and not the EMS page-frame manager used for expanded memory (that role belongs to EMM386.EXE or similar). Step-by-Step Solution: Load HIMEM.SYS in CONFIG.SYS to expose XMS services.Applications or memory managers call XMS API to allocate extended memory blocks.HIMEM.SYS facilitates HMA usage, letting DOS load high to free conventional memory.EMS remains separate and typically requires EMM386.EXE. Verification / Alternative check: MS-DOS MEM command shows XMS available once HIMEM.SYS is active; removing the driver eliminates XMS access. Why Other Options Are Wrong: ANSI emulation belongs to ANSI.SYS. Expanded memory requires EMM386.EXE; HIMEM.SYS handles extended memory. Code page switching is managed by DISPLAY.SYS and related utilities. Common Pitfalls: Confusing EMS with XMS. EMS uses paging in a 64 KB page frame; XMS uses linear extended memory and HMA. Final Answer: Manages the use of extended memory

Question 10

SCSI capacity planning: how many total devices can share a single narrow SCSI bus (including the host adapter)?

Accepted Answer

Introduction / Context: SCSI buses support multiple devices with unique IDs. The allowable count depends on whether the bus is narrow (8-bit) or wide (16-bit). The question targets the classic narrow SCSI case used in many PCs and workstations. Given Data / Assumptions: Narrow SCSI bus (IDs 0 through 7). The host adapter itself occupies one ID. Correct termination and cabling are assumed. Concept / Approach: Narrow SCSI provides 8 IDs total. One is used by the host adapter (often ID 7), leaving up to seven additional devices. Wide SCSI allows 16 IDs (0–15) including the adapter. Because the question does not specify wide SCSI, the standard answer for narrow SCSI is 8 total devices including the controller. Step-by-Step Solution: List valid IDs: 0–7 → total 8.Assign one ID to the host adapter → remaining 7 for peripherals.Ensure no duplicate IDs to avoid bus contention.Terminate at both physical ends of the bus only. Verification / Alternative check: Inspect the SCSI BIOS or OS hardware manager to see IDs and verify that the count does not exceed 8 on a narrow bus. Why Other Options Are Wrong: 1: Far below capacity. 10 or 20: Exceeds narrow SCSI limits. All of the above: Self-contradictory; only one value can be correct. Common Pitfalls: Confusing wide SCSI capacities with narrow SCSI and forgetting that the adapter counts toward the total device limit. Final Answer: 8

Question 11

PC troubleshooting workflow: what is the most logical first step when diagnosing a user’s problem?

Accepted Answer

Introduction / Context: Effective troubleshooting follows a structured process: identify, isolate, resolve, and verify. The first step sets the tone for an efficient diagnosis and prevents unnecessary changes to a system. Given Data / Assumptions: A PC exhibits a fault reported by a user. No prior diagnostics have been performed. Standard helpdesk methodology (gather symptoms, environment, and recent changes). Concept / Approach: Start by clearly defining the problem: what happened, when it started, what changed, what exact messages appear, and how reproducible it is. This establishes scope and prevents random alterations that could worsen the issue. Only after definition do you proceed to targeted checks like CMOS settings, application specifics, logs, and hardware tests. Step-by-Step Solution: Interview the user and capture the exact symptoms and timeline.Reproduce the issue, noting triggers and frequency.Document environment: OS, patches, hardware, peripherals.Form a hypothesis; then test with minimal, reversible actions. Verification / Alternative check: After defining and replicating the problem, targeted diagnostics (event viewer, SMART status, memory tests) validate or falsify hypotheses quickly. Why Other Options Are Wrong: Check CMOS prematurely changes variables without understanding the issue. Call the vendor before basic scoping wastes time and weakens your case. Define applications used is useful but is a subset of defining overall circumstances; it is not the broader first step. Common Pitfalls: Jumping into fixes without reproducing the problem, leading to confirmation bias and missed root causes. Final Answer: Define the circumstances of the problem

Question 12

Dot-matrix printer care: which part should never be lubricated during maintenance?

Accepted Answer

Introduction / Context: Dot-matrix printers use an impact printhead with multiple tiny pins driven by solenoids to strike an ink ribbon. Proper lubrication keeps motion smooth, but lubrication of the wrong parts can destroy print quality and the mechanism itself. Given Data / Assumptions: Standard dot-matrix printer with a multi-pin impact head. Manufacturer-recommended lubricants and schedules exist for rails and bearings. Printhead pins operate in precise bushings and must remain clean. Concept / Approach: Carriage rails and certain bearings may require approved, light lubrication to reduce friction. However, the printhead pins must never be lubricated. Oil attracts dust and ribbon debris, causing sticking pins, smeared characters, and misfires. Printheads are typically serviced by cleaning with approved solvents, not by applying oil or grease to the pins. Step-by-Step Solution: Clean and lightly lubricate carriage rails per the service manual.Inspect carriage and paper feed bearings; apply manufacturer-approved lubricant sparingly if specified.Do not lubricate printhead pins; clean the printhead assembly using approved method only.Test print to confirm sharp, consistent dot formation. Verification / Alternative check: After proper maintenance, the carriage glides smoothly and test patterns show crisp dots with no missing columns. Oiled pins often show fuzzy text and sticking columns. Why Other Options Are Wrong: Carriage rails / bearings: Often require careful lubrication. Paper advance bearings: May receive lubrication per vendor guidance. None of the above: Incorrect because pins should not be lubricated. Common Pitfalls: Over-lubrication leading to oil migration onto the ribbon or paper path, and using non-approved oils that gum up over time. Final Answer: Printhead pins

Question 13

Measuring a good 2 A fuse with a digital multimeter set to resistance (Ω), range 20k: what reading should you expect?

Accepted Answer

Introduction / Context: A quick continuity test confirms whether a fuse is intact. When using a DMM on an ohms range, a good fuse should present very low resistance. Understanding expected readings prevents misdiagnosis due to range selection or probe contact issues. Given Data / Assumptions: DMM selector is on DC/Ω, resistance range 20k (20,000 Ω full scale). Fuse rating 2 A, typical cold resistance near 0 Ω. Probes and contact points clean and firmly connected. Concept / Approach: Continuity of a fuse is essentially a near-short. On a high-ohms range, a near-zero resistance will display ~0.00 on many meters. Any significant nonzero resistance suggests a bad probe contact or a partially damaged fuse (rare). An open fuse reads over-range (often shown as OL). Step-by-Step Solution: Zero-check the meter by touching probe tips together; reading should approach 0.00.Place probes across the fuse terminals.Interpret display: ~0.00 indicates a good fuse; OL indicates open fuse.If uncertain, repeat on a lower ohms range for more resolution. Verification / Alternative check: Use the continuity beeper mode; a solid tone confirms near-zero resistance. Visual inspection of the fuse element can corroborate. Why Other Options Are Wrong: 0.02 / 0.20 / 2.00: Suggests significant resistance; atypical for a good fuse and likely due to contact resistance or wrong interpretation. None of the above: Incorrect because ~0.00 is expected. Common Pitfalls: Measuring in-circuit (parallel paths skew results), dirty probe tips, and using continuity on fuses with surface oxidation causing intermittent readings. Final Answer: 0.00

Question 14

Installing a second IDE (PATA) hard drive: what must you do before attaching it on the same cable as the first drive?

Accepted Answer

Introduction / Context: Older IDE (PATA) interfaces allow two devices per channel on a 40/80-conductor ribbon. Correct jumpering prevents bus contention and ensures the BIOS recognizes both drives correctly. Given Data / Assumptions: Two PATA drives on one IDE channel (one cable). Traditional Master/Slave or Cable Select options available. Standard PC BIOS detection for PATA devices. Concept / Approach: With Master/Slave mode, the second drive must be jumpered to Slave and the first to Master. Alternatively, with Cable Select (CS) both drives are set to CS and cable position determines role, but the question implies the classic Master/Slave practice. Step-by-Step Solution: Power off and ground yourself to avoid ESD.Set the second drive’s jumper to Slave; confirm the first is Master (or both CS with an 80-wire CS cable).Connect the ribbon cable ensuring pin-1 alignment; attach power.Enter BIOS and auto-detect both drives; assign boot order as needed. Verification / Alternative check: On POST, both drives should enumerate. The OS disk manager will show both devices; drive letters are assigned by the OS, not set in CMOS directly. Why Other Options Are Wrong: IDE configuration software: Not required for basic jumpering. Define as D: in CMOS: CMOS does not assign letters; the OS does. End connector only: Not mandatory; middle connector works, especially with CS cabling. Common Pitfalls: Mixing CS and Master/Slave modes, wrong jumper settings, and using 40-wire cables with ATA modes needing 80-wire cables. Final Answer: Set the master-slave jumper to slave on the second drive

Question 15

Field-replaceable units (FRUs): which of the following is best classified as an input/output device?

Accepted Answer

Introduction / Context: FRUs are components designed for quick replacement. Categorizing them by function helps in troubleshooting and inventory planning. The question asks which listed FRU is explicitly an I/O device—something that interfaces the system bus to external or peripheral buses. Given Data / Assumptions: Video board primarily outputs display signals. SCSI host adapter connects system to storage/peripheral SCSI bus (bidirectional). CPU is the central processor, not an I/O controller. Concept / Approach: An I/O device mediates data transfer between the CPU/memory subsystem and external devices. A SCSI host adapter provides this interface, handling command, data, and status phases in both directions. A video board primarily outputs frames (with limited input such as EDID reads, but it is not generally termed an I/O controller). The CPU executes instructions and coordinates I/O but is not itself an I/O device. Step-by-Step Solution: Identify components that directly implement a peripheral bus protocol.SCSI host adapter implements the SCSI protocol and DMA/PIO transfers.Conclude it is the I/O FRU among the choices.Therefore, select the host adapter. Verification / Alternative check: System device manager lists the SCSI adapter under storage controllers (I/O), not under processors or display adapters. Why Other Options Are Wrong: Video board: Primarily output; not a general I/O bus controller. CPU: Core compute element; not categorized as an I/O device. All of the above / None: Over-broad or incorrect. Common Pitfalls: Assuming any card is “I/O.” Many GPUs are output-only devices from a classification standpoint. Final Answer: SCSI host adapter

Question 16

USB vs. IEEE 1394 (FireWire): what is the most significant difference between the standards in classic PC contexts?

Accepted Answer

Introduction / Context: Legacy PC interfaces offered two popular serial buses: USB (notably USB 1.1 at 12 Mb/s at the time) and IEEE 1394 FireWire (commonly 400 Mb/s, later 800 Mb/s). Understanding their comparative speed and features informs device selection for storage, video capture, and audio interfaces. Given Data / Assumptions: Comparison refers to the classic era: USB 1.1 vs IEEE 1394a (FireWire 400). Typical peripherals: scanners, cameras, external drives. Both buses support hot plugging in their standard implementations. Concept / Approach: In that historical context, IEEE 1394 was significantly faster (up to 400 Mb/s, later 800 Mb/s) and provided isochronous transfer modes useful for real-time audio/video. USB 1.1 topped out at 12 Mb/s. Both were plug-and-play and hot-swappable in mainstream OS support, so speed was the most striking difference then. Step-by-Step Solution: Identify maximum signaling rates: USB 1.1 = 12 Mb/s; FireWire 400 = 400 Mb/s.Note isochronous support on IEEE 1394 benefiting A/V workloads.Recognize both standards support hot swapping and plug-and-play.Therefore, the most significant difference cited is speed in that timeframe. Verification / Alternative check: Benchmarks of external HDDs and DV camcorders from that era consistently favored IEEE 1394 for sustained transfers. Why Other Options Are Wrong: USB does not support USB: Nonsensical. USB is plug and play: True but not unique; IEEE 1394 is also plug and play. IEEE 1394 is hot swappable: True but USB is hot swappable too; not the distinguishing factor. Common Pitfalls: Comparing later USB 2.0/3.x speeds retroactively; the question frames a classic comparison where FireWire was faster. Final Answer: IEEE 1394 is faster

Question 17

PC hardware maintenance: What is the safest product to clean Mylar-protected LCD screens?  When removing finger smudges, dust, or light grime from a liquid crystal display (LCD) that has a Mylar or other plastic anti-glare/anti-scratch overlay, whic…

Accepted Answer

Introduction / Context: LCD panels often include a Mylar or similar polymer overlay to diffuse reflections and protect the surface. Choosing the correct cleaner matters because harsh chemicals and abrasives can cloud, craze, or strip this coating. This question tests practical hardware maintenance and ESD-safe cleaning practice. Given Data / Assumptions: The LCD has a plastic (Mylar) protective layer, not bare glass. Goal: safely remove light dirt, skin oils, and dust without scratching or chemically attacking the coating. Technician has access to common field items: ammonia glass sprays, general cleansers, alcohol wipes, and anti-static wipes. Concept / Approach: Plastics are sensitive to solvents (ammonia, alcohols, ketones) and abrasives. Best practice is to use anti-static, lint-free wipes made for electronics, often pre-moistened with neutral, plastic-safe solutions. They clean while minimizing static charge buildup that could attract dust or risk ESD near open equipment. Step-by-Step Solution: Avoid aggressive chemicals that can haze or delaminate a Mylar coating.Use anti-static wipes designed for displays to gently lift oils without scratching.Wipe in one direction with light pressure; do not flood liquid into bezels.Finish with a dry lint-free cloth if needed to remove remaining streaks. Verification / Alternative check: Manufacturer care guides routinely warn against ammonia and alcohol on coated plastics. Testing on a small, inconspicuous area confirms compatibility. Anti-static wipes are marketed for monitors and optical plastics, validating their suitability. Why Other Options Are Wrong: Ammonia window cleaner: can cloud or yellow the polymer and leave streaks. Non-abrasive cleanser: vague; many household products still contain surfactants/solvents not rated for plastics. Alcohol-impregnated wipes: can dry and craze some plastic coatings over time. None of the above: incorrect because anti-static wipes are appropriate. Common Pitfalls: Using paper towels (abrasive), excessive liquid, or spraying the screen directly. Always power down, disconnect AC, and avoid pressing hard on the panel. Final Answer: Anti-static wipes

Question 18

Electrostatic discharge (ESD) awareness: When is ESD risk the greatest?  Consider a typical electronics work area. Under which ambient condition is the likelihood of damaging electrostatic discharge highest when handling components or PCBs?

Accepted Answer

Introduction / Context: Electrostatic discharge can silently damage semiconductors. Environmental factors strongly influence how quickly static charges build up on people and materials. Knowing the worst-case condition helps technicians set preventive controls. Given Data / Assumptions: We compare broad conditions like humidity and time of day. Humans and insulators can accumulate charge via triboelectric effects. Goal: identify the condition that maximizes static buildup and ESD risk. Concept / Approach: Dry air is a poor conductor. At low humidity, surfaces retain charge because there is not enough moisture to dissipate it. At higher humidity, a thin conductive film of water molecules allows charges to bleed off. Therefore, low relative humidity produces the highest ESD risk. Step-by-Step Solution: Recognize triboelectric charge builds from motion, friction, and separation of materials.Assess dissipation: humidity increases surface conductivity and reduces charge retention.Conclude the highest risk occurs at low humidity (e.g., winter, air-conditioned rooms).Mitigate with humidification, ESD mats, wrist straps, and ionizers. Verification / Alternative check: ESD control standards (e.g., common industry practices) recommend maintaining RH around 40–60% to reduce static; audits show spike in ESD events as RH drops below ~30%. Why Other Options Are Wrong: High humidity: charges dissipate more readily, so risk decreases. Daytime / Night time: time of day is not the determining factor; the controlling factor is environmental dryness and materials handling. None of the above: incorrect because low humidity is clearly the highest risk. Common Pitfalls: Assuming colder temperatures are the root cause. It is the associated dryness (low RH) that matters. Also, wearing synthetics and rolling office chairs amplify risks in dry rooms. Final Answer: Low humidity

Question 19

Troubleshooting no-video PCs: Identify the least likely root cause  A desktop PC powers on but shows no video on the display. Among common culprits, which is the least likely to cause a no-video symptom during POST or boot?

Accepted Answer

Introduction / Context: When a PC shows no video, a technician prioritizes failures that occur before or during the Power-On Self-Test (POST). Understanding which subsystems are involved before the disk is accessed helps triage quickly. Given Data / Assumptions: System powers up but display remains blank or out of sync. We are considering causes from power, CPU, memory, and video to storage. POST typically initializes CPU, chipset, memory, and video before touching the OS drive. Concept / Approach: No-video conditions are most often due to issues on the path to generating a video signal: seating of the GPU, RAM errors preventing POST beeps, motherboard/CPU faults, or inadequate power. Storage devices are initialized later; a failed hard drive usually shows video with an error like “No boot device.” Step-by-Step Solution: Check physical video connections and GPU seating first.Verify power rails and look for POST codes/beeps indicating memory or CPU faults.Recognize that disk access occurs after basic hardware init; a dead HDD rarely prevents any video output.Therefore, among the options, a crashed hard drive is least likely to cause no video. Verification / Alternative check: Bench tests with a known-good bootable USB often still produce video and BIOS screens even when the HDD is missing or failed, confirming that storage is not a prerequisite for video. Why Other Options Are Wrong: Loose video card: common cause of black screen. Defective RAM (bank zero): prevents POST, leading to no video and beep codes. Defective CPU: system cannot execute POST; results in no-video. Low AC outlet power: can cause unstable PSU output and no initialization. Common Pitfalls: Spending time swapping HDDs early. Always verify POST, beeps, and display output before storage troubleshooting. Final Answer: Crashed hard drive

Question 20

Preventing data loss from power interruptions: Which device should you deploy?  To avoid corrupted files or unexpected shutdowns when the mains power drops momentarily, what hardware protection is most appropriate for a workstation or small server?

Accepted Answer

Introduction / Context: Power anomalies such as sags and brief outages can abruptly shut down computers, risking file system corruption and data loss. Choosing the right protective device is essential for continuity and graceful shutdowns. Given Data / Assumptions: Requirement: ride through short power losses and allow orderly system shutdown. Environment: single workstation or small server. Available choices include surge suppression and battery-based solutions. Concept / Approach: A UPS (Uninterruptible Power Supply) provides stored energy via batteries and an inverter, keeping equipment powered during short interruptions and signaling the OS to shut down cleanly during extended outages. Surge protectors only clamp spikes; they do not supply energy when voltage disappears. Step-by-Step Solution: Identify threat: momentary power loss corrupts data.Map solution: device must supply power, not merely filter it.Select UPS: it converts DC battery to AC, bridging the gap and enabling system shutdown scripts.Implement monitoring via USB/serial for automated OS responses. Verification / Alternative check: UPS logs show transfer events where loads continue without reboot; file systems remain consistent. Surge strips alone show no such capability and computers crash on power loss. Why Other Options Are Wrong: Surge protector: clamps transients but cannot supply power during outages. Multiple SIMMs: RAM quantity does not address power continuity. Data guard system: vague/nonstandard; not a power continuity device. None of the above: incorrect because a UPS directly addresses the requirement. Common Pitfalls: Confusing surge suppression with backup power and undersizing UPS capacity. Always size for wattage and runtime, test shutdown integration, and replace batteries periodically. Final Answer: Battery back-up unit (UPS)

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