Question 1

Serial communications terminology: In RS-232 handshaking, what does the acronym RTS stand for?

Accepted Answer

Introduction / Context: RS-232 serial links use modem control signals for hardware flow control. Recognizing the meaning of common control lines is essential when diagnosing serial device communications and cabling issues. Given Data / Assumptions: The question refers to a standard RS-232 control line. Common pairs include RTS/CTS and DTR/DSR. Concept / Approach: RTS stands for Request to Send. A Data Terminal Equipment (DTE) device asserts RTS to indicate it wants to transmit; the peer responds with CTS (Clear to Send) if the channel is available. This mechanism prevents buffer overruns and coordinates half-duplex links. Step-by-Step Solution: Identify RTS within the RTS/CTS pair.Recall the expansion: Request to Send.Select the correct option. Verification / Alternative check: Serial breakout boxes and protocol analyzers label RTS as Request to Send; driver settings reference RTS/CTS flow control. Why Other Options Are Wrong: They are unrelated phrases and not RS-232 nomenclature. Common Pitfalls: Confusing RTS with CTS or with DTR/DSR, which serve different roles (data terminal ready / data set ready). Final Answer: Request to send

Question 2

Operating system upgrades: Which of the following is LEAST likely to interfere with upgrading to a newer DOS version?

Accepted Answer

Introduction / Context: Upgrading legacy DOS systems can be impacted by hardware compatibility, BIOS behavior, and storage configurations. Correctly identifying non-issues saves time and reduces risk during migration steps such as boot disk preparation and SYS/FORMAT operations. Given Data / Assumptions: Standard PC with ROM BIOS and video controller. Some systems used drive compression utilities that affect boot and file access. Backup files are simply data stored elsewhere on the disk or external media. Concept / Approach: ROM BIOS and certain video adapters may require specific DOS versions or drivers. Compressed drives (e.g., DoubleSpace/DriveSpace or third-party tools) can complicate boot loaders and file access during upgrades. By contrast, existing backup files are benign and do not interfere with the upgrade—indeed, they are recommended before any OS change. Step-by-Step Solution: List potential blockers: firmware quirks, driver support, compressed volumes.Recognize backups are harmless and desirable.Choose the option least likely to cause issues: Existing backup files. Verification / Alternative check: Vendor upgrade notes often warn about drive compression and video/BIOS compatibility but never about the mere presence of backups. Why Other Options Are Wrong: ROM BIOS or video may require patches; compressed drives can break boot sequences if mishandled. Common Pitfalls: Forgetting to uncompress or provide the right drivers before upgrading; misidentifying backups as “unused files.” Final Answer: Existing backup files

Question 3

Laser printer diagnostics: A laser printer outputs a completely black page. Which cause is most likely?

Accepted Answer

Introduction / Context: In electrophotographic (laser) printing, several charging stages prepare and develop the image on the drum before transfer and fusing. Recognizing symptom-to-stage relationships speeds troubleshooting and parts replacement. Given Data / Assumptions: Total page is uniformly black. Printer otherwise feeds and fuses normally. Focus on the most probable single-point failure. Concept / Approach: The primary charge (corona or charge roller) applies a uniform charge to the drum. The laser then selectively discharges areas to form the latent image. If the primary charging stage fails (no power to the primary corona/roller), the drum is not correctly precharged and tends to attract toner across the entire surface during development, producing a solid black page. By contrast, a failed imaging laser usually yields blank pages (no discharging, toner repelled), not black ones. Transfer issues affect how the image gets onto paper, not whether it is all black. Step-by-Step Solution: Identify the uniformity of the fault: full black coverage implies charging/develop bias failure.Map to subsystem: primary charge stage not working.Conclude: No power to primary corona is the most likely cause. Verification / Alternative check: Swap in a known-good charge assembly or perform engine test pages; service manuals list this symptom for primary charge failures. Why Other Options Are Wrong: Imaging laser malfunction tends to produce blank (white) pages. Low toner reduces density, not creates black pages. Transfer corona failure leaves image on drum or causes faint prints, not a solid black page. Common Pitfalls: Replacing toner unnecessarily or suspecting the formatter when the electrophotographic core is at fault. Final Answer: no power to the primary corona

Question 4

Laser printing process: During the fusing stage of a laser printer, how is toner affixed to the paper?

Accepted Answer

Introduction / Context: Understanding the seven-step laser printing process helps pinpoint faults and explains consumable wear. Fusing is the final stage where the toner image becomes permanent on the sheet. Given Data / Assumptions: Toner is a thermoplastic powder with pigments. A heated fuser roller and a pressure roller form the fusing assembly. The question asks how toner is finally attached to paper. Concept / Approach: In the fusing stage, heat softens the thermoplastic toner while pressure presses it into the paper fibers. This combination melts and embeds the toner, creating a durable bond. Electrical bonding describes earlier stages (charging/transfer), not the mechanical/thermal fixing. Glue is not used, and toner is not sprayed at high pressure in fusing. Step-by-Step Solution: After transfer, the loose toner image sits on the sheet.Paper passes between a heated fuser roller and a pressure roller.Heat raises toner above its glass transition; pressure embeds it into fibers.Result: toner is melted into the paper, forming a permanent image. Verification / Alternative check: Unfused images (before fuser) can be smudged by touch; after proper fusing, rubbing does not smear. Service temperatures and fuser sleeve design confirm the melt process. Why Other Options Are Wrong: Dry pressed lacks heat; electrically bonded is inaccurate at this stage; glued and sprayed do not describe laser printing mechanics. Common Pitfalls: Associating transfer corona action with fusing, or misdiagnosing fuser failure when the problem is actually low toner or humidity. Final Answer: melted into the paper

Question 5

PC hardware safety during thunderstorms:  How can you completely protect a desktop or laptop computer from electrical-storm damage and surge entry through any connected cable?

Accepted Answer

Introduction / Context: Electrical storms can inject large voltage spikes and common-mode surges into equipment through any conductive path. This question tests best-practice surge protection for PCs beyond basic power-strip usage. Given Data / Assumptions: A thunderstorm is in progress or imminent. The PC may have multiple external connections: AC mains, Ethernet, coax, phone/DSL, USB, peripherals, and printers. The goal is total protection, not just risk reduction. Concept / Approach: A surge can enter through any cable: power, network, coax, or phone lines. Surge protectors reduce risk but cannot guarantee protection from severe lightning-induced transients. The only way to ensure no energy path into the device is to physically disconnect every external cable, including the AC power cord and all data/communication lines. Step-by-Step Solution: Identify all conductive paths: AC mains, Ethernet, phone/coax, USB, HDMI, printers.Recognize that surge devices have clamping limits and let-through voltages.For absolute protection, remove the paths by unplugging every external connection.Place equipment away from conductive paths until the storm passes. Verification / Alternative check: Electrical safety guidelines consistently state that only complete disconnection ensures isolation from lightning surges. Surge protectors and UPS units add protection but cannot guarantee immunity during a direct or close strike. Why Other Options Are Wrong: Turn off AC power switch only: still connected; surge can couple through the cord. Use a surge protector: mitigates, does not guarantee total protection. Disconnect AC power cable only: data/coax/phone lines remain surge paths. None of the above: incorrect because full disconnection is correct. Common Pitfalls: Assuming a premium surge strip makes gear invincible; forgetting Ethernet or phone lines which often carry damaging surges; leaving laptop power bricks plugged in with the DC plug inserted. Final Answer: Disconnect all external cables and power cords

Question 6

PC power-supply diagnostics:  To check AC ripple on a computer's DC power rails with a multimeter, which meter setting should you select?

Accepted Answer

Introduction / Context: Switch-mode PC power supplies output DC voltages, but excessive AC ripple indicates failing capacitors or poor regulation. Measuring ripple correctly is vital for troubleshooting random resets and data errors. Given Data / Assumptions: You need to measure residual AC ripple superimposed on DC outputs (for example, +12 V, +5 V, +3.3 V). A standard handheld multimeter is available. Safety and correct measurement technique are required. Concept / Approach: Ripple is the AC component riding on a DC rail. To see it with a multimeter, set the meter to AC voltage and measure across the rail and ground. The DC setting measures average DC and largely ignores high-frequency AC; resistance and capacitance scales are irrelevant to in-circuit ripple measurement. Step-by-Step Solution: Power the PC or bench PSU on under a typical load.Set the multimeter to AC volts.Probe between the DC rail and ground; read AC magnitude (ideally very low).Compare against acceptable ripple limits or reference PSU specs. Verification / Alternative check: An oscilloscope provides a far clearer picture of ripple frequency and amplitude; however, a DMM on AC volts is a quick screening tool to flag abnormal ripple. Why Other Options Are Wrong: DC voltage scale: reads the DC level, not the AC ripple content. OHM scale: used on de-energized circuits; not for ripple on live rails. Farad scale: for capacitance, not ripple voltage. None of the above: incorrect because AC voltage is correct. Common Pitfalls: Measuring ripple with the system idle (load-dependent); placing probes unsafely near primary side; drawing conclusions from noisy DMM readings without cross-checking with a scope. Final Answer: AC voltage

Question 7

Disk performance and file layout:  Which description best defines a fragmented hard drive in terms of how files are stored on disk?

Accepted Answer

Introduction / Context: File-system fragmentation affects performance by scattering file data across the disk, increasing seek time. Understanding what fragmentation is (and isn’t) helps in diagnosing slow systems and applying the correct remedy. Given Data / Assumptions: Conventional spinning hard drive with cluster-based file system (e.g., FAT/NTFS). Symptoms: slower file access and longer boot times. No evidence of physical drive failure is assumed. Concept / Approach: Fragmentation means file data is split into multiple non-contiguous extents. The disk head must perform additional seeks to assemble a file, degrading throughput. This is a logical layout issue, not necessarily data corruption or platter damage. Step-by-Step Solution: Define fragmentation: non-consecutive cluster allocation for files.Relate to performance: more seeks, lower effective throughput.Identify remedy: defragmentation tools reorder clusters contiguously.Confirm the correct option: non-consecutive storage of files. Verification / Alternative check: OS defragmenters visualize files as many fragments. After defrag, the same files occupy longer contiguous runs, reducing head movement and improving access times. Why Other Options Are Wrong: Corrupted files: integrity issue, not fragmentation definition. Damaged platters or all clusters damaged: indicates hardware faults, not fragmentation. None of the above: incorrect because one option precisely matches the definition. Common Pitfalls: Confusing fragmentation with bad sectors; thinking SSDs need defrag (they do not benefit and may wear unnecessarily; they use TRIM and wear-leveling instead). Final Answer: Files are not stored in consecutive clusters on the disk

Question 8

Relative access speeds of common PC storage/memory:  Which component typically provides the fastest data access time during normal computer operation?

Accepted Answer

Introduction / Context: The memory/storage hierarchy prioritizes speed at the top (CPU caches, RAM) and capacity at the bottom (disks, optical). Recognizing which layer is fastest explains why programs and data are loaded into RAM for execution. Given Data / Assumptions: Compare typical consumer hardware: DRAM, HDD, optical drives, ROM. Metrics considered: latency and throughput. Ignore specialized cases (e.g., RAM disks, XIP from fast NOR). Concept / Approach: RAM operates at nanosecond-scale latency and very high bandwidth, orders of magnitude faster than magnetic or optical storage with millisecond-scale seeks. ROM devices are not used as primary working memory and usually have slower interfaces than main memory. Step-by-Step Solution: Contrast latencies: RAM (ns) vs. HDD (ms) vs. optical (ms).Contrast bandwidth: RAM in GB/s vs. disks in MB/s.Operational use: code and data brought into RAM for execution.Select RAM as the fastest option. Verification / Alternative check: Benchmarks consistently show memory bandwidth in multi-GB/s, while even modern disks/opticals are far slower. SSDs narrow the gap but still trail RAM significantly. Why Other Options Are Wrong: Hard disk/CD-ROM: slow due to mechanical/optical access. ROM: slower interface, read-only, not working memory. None of the above: incorrect because RAM is clearly fastest. Common Pitfalls: Assuming flash-based storage equals RAM speeds; they remain slower in both latency and sustained bandwidth. Final Answer: RAM

Question 9

Electrostatic discharge (ESD) handling:  Which action is most likely to cause ESD damage to an integrated circuit (IC) during handling and transport?

Accepted Answer

Introduction / Context: ESD is a silent killer of sensitive semiconductor junctions. Proper packaging and handling practices prevent latent defects and immediate device failure. Given Data / Assumptions: We are handling loose ICs or boards. Packaging may be insulating, dissipative, or conductive. Grounding practices are available (mats, wrist straps). Concept / Approach: Non-conductive (insulating) plastic can accumulate high static charge. Placing ICs in such bags risks sudden discharge into device pins. Proper ESD packaging is conductive or static dissipative, which equalizes charge slowly and safely. Grounded mats and chassis touch (after proper connection to earth/ESD ground) help drain body charge. Step-by-Step Solution: Identify unsafe packaging: non-conductive plastic accumulates charge.Prefer pink/black ESD-safe bags (dissipative/conductive).Use wrist strap and grounded mat; handle by edges.Avoid insulating materials that build charge. Verification / Alternative check: ESD control standards (ANSI/ESD S20.20) recommend dissipative or conductive packaging and grounded workstations. Insulating plastics are discouraged for sensitive devices. Why Other Options Are Wrong: Grounded mat and chassis touch: reduce potential difference. Repeated sags in current: that is a power-quality issue, not ESD. None of the above: incorrect since the insulating bag is a known hazard. Common Pitfalls: Confusing pink anti-static (dissipative) with plain clear plastic; forgetting to ground oneself before handling parts; mixing ESD-safe and non-ESD bags. Final Answer: Placing an IC in a non-conductive plastic bag

Question 10

Boot options and firmware support:  If a computer's BIOS/UEFI firmware supports optical boot, can the system boot directly from a CD-ROM?

Accepted Answer

Introduction / Context: Boot device selection depends on firmware capabilities. Many systems support booting from optical media for OS installation and recovery. Given Data / Assumptions: The firmware provides an option to boot from CD/DVD. Media is bootable (proper boot catalog and filesystem). Optical drive is functioning and connected. Concept / Approach: When BIOS/UEFI supports a device as a boot source and the device contains bootable media, the firmware loads boot code from that medium. Optical boot has been standard for decades, using El Torito boot specification on BIOS systems and appropriate boot entries for UEFI. Step-by-Step Solution: Enter firmware setup; enable/choose CD/DVD as a boot device.Insert a bootable CD/DVD with valid boot image.Save and reboot; firmware executes optical boot code.Proceed with installer or recovery environment. Verification / Alternative check: Most OS installers (Windows, Linux distributions) provide optical boot media. UEFI also supports optical boot with appropriate bootloaders. Why Other Options Are Wrong: False: contradicts long-standing firmware features. Other options: not relevant; the statement is clear and correct. Common Pitfalls: Non-bootable discs, incorrect boot order, legacy/UEFI mode mismatches, or disabled optical controllers can prevent boot even if supported. Final Answer: True

Question 11

Legacy NIC configuration (I/O ports):  When manually configuring a new ISA-era network interface card, which of the following is a valid hexadecimal I/O base address commonly used by NICs?

Accepted Answer

Introduction / Context: Older ISA NICs required selecting I/O base addresses and IRQs that did not conflict with existing devices. Recognizing common ranges helps avoid clashes with serial and parallel ports. Given Data / Assumptions: We are configuring a legacy ISA NIC (for example, NE2000-compatible). Common serial/parallel port addresses are reserved. We aim to choose a typical NIC I/O address. Concept / Approach: Many NICs used I/O bases like 0x300, 0x320, 0x340, and 0x360. Meanwhile, 0x3F8 (COM1) and 0x2F8 (COM2) are serial ports, and 0x378 is LPT1. Selecting 0x360 avoids conflicts and aligns with common NIC settings. Step-by-Step Solution: List reserved ports: 0x3F8 (COM1), 0x2F8 (COM2), 0x378 (LPT1).List typical NIC ports: 0x300/0x320/0x340/0x360.Pick one from the NIC list that is not reserved: 0x360.Apply in NIC setup utility or jumpers/EEPROM configuration. Verification / Alternative check: Vendor manuals for ISA NICs cite these bases as defaults/options. System resource viewers confirm conflicts if a reserved address is selected. Why Other Options Are Wrong: 0x378: parallel port (LPT1), usually occupied. 0x2F8 and 0x3F8: serial ports COM2 and COM1, respectively. None of the above: incorrect because 0x360 is valid and common. Common Pitfalls: Forgetting to change IRQ alongside I/O base; ignoring BIOS/OS resource reservations; confusing decimal/hex notation. Final Answer: 0x360

Question 12

Setting SCSI IDs with jumpers:  SCSI IDs start at 0. What jumper pattern selects the fourth SCSI ID on a 3-bit ID block (weights 4-2-1)?

Accepted Answer

Introduction / Context: SCSI devices use binary ID selection. Understanding how to set jumpers avoids bus conflicts and ensures proper device ordering on the chain. Given Data / Assumptions: SCSI IDs are zero-based: 0, 1, 2, 3, ... Three jumpers represent binary weights 4, 2, and 1 (from MSB to LSB). We want the fourth ID counting from 0. Concept / Approach: Counting from 0: the fourth ID is 3 in decimal (0,1,2,3). Convert 3 to binary using weights 4-2-1: 3 = 2 + 1 = 011. Therefore, enable the 2 and 1 jumpers, leave the 4 jumper off. Step-by-Step Solution: Enumerate IDs: 0, 1, 2, 3 → fourth is 3.Convert decimal 3 to binary with weights 4-2-1.3 = 2 + 1 → set jumpers for 2 and 1 → pattern 011.Verify on device label/silk-screen and terminate bus ends as needed. Verification / Alternative check: Most SCSI devices print a truth table on the chassis. Selecting ID 3 aligns with pattern 011 on 3-bit selectors. Why Other Options Are Wrong: 110: equals 6 (4 + 2), not 3. 010: equals 2 only. 101: equals 5 (4 + 1). 001: equals 1. Common Pitfalls: Misreading bit order (left-to-right vs. right-to-left), forgetting the host adapter also consumes one ID, and neglecting termination rules. Final Answer: 011

Question 13

Cable interference basics:  If a printer cable runs too close and parallel to a power cable, what problem is most likely to occur?

Accepted Answer

Introduction / Context: Signal cables placed near power conductors can pick up noise. Understanding interference mechanisms helps with practical cabling and troubleshooting printer communication errors. Given Data / Assumptions: Printer cable (parallel or USB) runs alongside AC mains cable. Cables are in close proximity for a meaningful length. Symptoms may include data retries or garbled output. Concept / Approach: Alternating current in power cables produces time-varying electromagnetic fields. Parallel routing with small separation increases inductive and capacitive coupling into signal lines, creating EMI that degrades signal integrity. Cross at right angles or separate physically to reduce coupling. Step-by-Step Solution: Identify coupling path: adjacent, parallel cable runs.Recognize the effect: induced noise into the data cable.Apply mitigation: increase separation, cross at 90°, use shielding/ferrites.Verify by rerouting and observing error reduction. Verification / Alternative check: EMC best practices and cabling standards recommend physical separation and perpendicular crossings to limit EMI. Ferrite beads on cables often help suppress common-mode noise. Why Other Options Are Wrong: ESD: sudden discharge events, not sustained coupling from nearby power lines. Parity error from RAM: unrelated to printer cabling. No effect: contradicted by well-known EMI coupling mechanisms. Common Pitfalls: Bundling power and signal cables together for neatness; ignoring ferrite cores; using excessively long, unshielded cables. Final Answer: EMI (Electromagnetic Interference)

Question 14

Fuse continuity check with a multimeter:  On a 5 A circuit, you remove the fuse and measure its resistance. If the fuse is healthy (not blown), what should the meter read approximately?

Accepted Answer

Introduction / Context: A fuse is intended to conduct with minimal resistance until a fault causes it to open. Measuring its resistance is a basic continuity test that confirms whether it is intact or blown. Given Data / Assumptions: The fuse is removed from the circuit before measurement. A standard digital multimeter is set to measure resistance. The fuse rating (5 A) does not imply its resistance equals 5 ohms. Concept / Approach: An intact fuse is essentially a short conductor. Its resistance is very low (typically a fraction of an ohm). A blown fuse is an open circuit and reads infinite or out of range. Therefore, a good fuse should read very close to 0 ohms (some meters may show 0.0 or a small residual like 0.1–0.3 ohms due to lead resistance). Step-by-Step Solution: Remove fuse from the holder to isolate it.Short meter leads together to note lead resistance (for reference).Measure across fuse end caps; compare to lead resistance.Reading near 0 ohms indicates continuity; infinite indicates blown fuse. Verification / Alternative check: Using the meter’s continuity beeper yields an audible tone on a good fuse and silence on a blown fuse; both methods agree with a near-zero ohm reading for a healthy fuse. Why Other Options Are Wrong: 5.0 ohms: far too high; would drop excessive voltage and dissipate power. 0.5 ohms: higher than expected for most small fuses; while some very large fuses can be milliohms, typical readings are near zero on DMM. All of the above: cannot be correct since the readings are mutually exclusive. Common Pitfalls: Measuring in-circuit (parallel paths distort reading); forgetting to subtract lead resistance; assuming the ampere rating relates directly to ohmic value. Final Answer: 0.0 (approximately zero ohms)

Question 15

PC hardware acronyms: In personal computer and hard-disk terminology, what does the acronym HDI stand for?

Accepted Answer

Introduction / Context: Technicians encounter many acronyms in storage technology. The acronym HDI is used in hard-disk engineering to describe a key reliability concern at very small flying heights. Knowing the correct expansion of HDI helps you interpret drive specifications, failure modes, and manufacturer documentation. Given Data / Assumptions: The context is personal-computer hard disks and their mechanics. We are expanding the acronym HDI as used in disk-drive literature. Other distractors mimic common support or networking terms but are unrelated. Concept / Approach: Inside a hard disk, the read/write head flies nanometers above the rotating platter on an air bearing. If the head ever contacts (or nearly contacts) the platter, the condition is termed head-to-disk interference. This phenomenon drives requirements for cleanliness, flatness, lubrication, ramp load/unload mechanisms, and shock protection. Therefore, HDI expands to head to disk interference, not the other options listed. Step-by-Step Solution: Identify domain: mechanical aspects of HDDs (not networking or customer support).Recall that HDI in disk engineering refers to interaction between head and disk surfaces.Select the option that states “Head to disk interference.” Verification / Alternative check: Drive design papers and failure analyses reference HDI when discussing head crashes, contamination control, and tribology at ultra-low flying heights. This confirms the expansion is tied to mechanical interference, not protocol or interface naming. Why Other Options Are Wrong: Half duplex interface: Networking/serial term, not HDD mechanics. Hard disk interface: Overly generic; the acronym HDI is not used this way. Help desk interference: Not a technical term. None of the above: Incorrect because a correct option is provided. Common Pitfalls: Confusing HDI with HDA (head-disk assembly) or with I/O interfaces like SATA/SCSI. Another pitfall is assuming HDI is a bus or protocol; it is a reliability/tribology term. Final Answer: Head to disk interference

Question 16

Legacy PC serial ports (I/O mapping): Which I/O base address is traditionally assigned to COM4 on IBM PC/AT–compatible systems?

Accepted Answer

Introduction / Context: Classic DOS/Windows systems mapped serial ports to fixed I/O base addresses. Understanding these defaults is useful when configuring legacy hardware, embedded consoles, or troubleshooting IRQ and port conflicts. Given Data / Assumptions: IBM PC/AT–style serial port conventions are assumed. COM ports are RS-232 interfaces mapped to standard base addresses. Hexadecimal notation uses suffix H. Concept / Approach: The conventional assignments are: COM1 = 3F8H, COM2 = 2F8H, COM3 = 3E8H, and COM4 = 2E8H. These addresses pair with typical IRQs (COM1/3 often IRQ4, COM2/4 often IRQ3), though systems could reconfigure them. Therefore, COM4 corresponds to 2E8H. Step-by-Step Solution: Recall standard map: COM1 3F8H, COM2 2F8H.Next pair: COM3 3E8H, COM4 2E8H.Select the base address 2E8H for COM4. Verification / Alternative check: Legacy BIOS setup screens, DOS MODE command outputs, and motherboard manuals confirm these canonical base addresses for serial ports. Why Other Options Are Wrong: 2F8H and 3F8H: Assigned to COM2 and COM1 respectively. 3E8H: Assigned to COM3. None of the above: Incorrect because 2E8H is correct. Common Pitfalls: Mixing up COM3 and COM4 addresses; assuming modern systems still use fixed ISA mappings; overlooking that some multi-I/O cards allowed remapping. Final Answer: 2E8H

Question 17

Cabling best practices: If a parallel/USB printer cable is routed too close to an AC power cable, which problem is most likely?

Accepted Answer

Introduction / Context: Power cables carrying alternating current create time-varying electromagnetic fields. Signal cables placed too close can pick up noise, reducing signal integrity. Understanding this helps with printer setup, AV gear, and general PC cabling. Given Data / Assumptions: Printer data cable runs parallel and adjacent to an AC mains cable. No special shielding or ferrite chokes are assumed. Symptoms could include intermittent printing, corrupted jobs, or device resets. Concept / Approach: Coupling between cables occurs via electric (capacitive) and magnetic (inductive) mechanisms. The coupled noise is termed electromagnetic interference (EMI). To mitigate, separate power and data paths, cross at right angles, shorten runs, or use shielded cables and ferrite beads. Step-by-Step Solution: Identify parallel routing with small separation—highest coupling case.Recognize induced noise appears as EMI on the signal cable.Select “EMI Electromagnetic Interference” as the correct effect. Verification / Alternative check: Re-route the cable away from power lines or add ferrites; if symptoms disappear, EMI was the cause. Oscilloscope probing can also reveal coupled noise spikes during load changes on the AC line. Why Other Options Are Wrong: ESD: Static shock events, not continuous coupling from adjacent power. Parity error: Memory/storage concept, not cabling interference terminology. No affect: Contrary to known coupling effects. None of the above: Incorrect because EMI is correct. Common Pitfalls: Bundling all cables in a single tie for neatness; using excessively long unshielded leads; ignoring ground loops when using shielded cables. Final Answer: EMI Electromagnetic Interference

Question 18

Port diagnostics tools: Which tool is commonly used to test serial (COM) and parallel (LPT) ports at the hardware level?

Accepted Answer

Introduction / Context: Troubleshooting legacy serial and parallel ports often requires verifying that the port can transmit and receive data electrically. Purpose-built test plugs simplify this by looping output pins back to input pins to validate the hardware path. Given Data / Assumptions: We need a direct hardware test for COM/LPT functionality. No external devices are required beyond the diagnostic plug and test software. The technician can access port settings and simple terminal/test utilities. Concept / Approach: A loopback (wrap) plug connects transmit to receive lines (and other handshakes) on serial ports, and appropriate pins on parallel ports, allowing self-test. If the port is healthy, data sent out returns exactly, confirming the transceiver, line drivers, and pins. This is fast and isolates cable/device variables. Step-by-Step Solution: Attach the correct loopback plug (DE-9/DB-25 for serial, Centronics/DB-25 for parallel).Run loopback/echo test software to transmit patterns.Verify that data received matches data sent, indicating a working port. Verification / Alternative check: Cross-check with a known-good external device or use a breakout box to visualize signal transitions on each line. Consistent results corroborate the loopback test. Why Other Options Are Wrong: High volt probe: For power/high-voltage circuits, not port logic testing. Cable scanner: Tests cable wiring continuity, not the port electronics themselves. Sniffer: Protocol analyzers capture traffic, not basic electrical loop tests. None of the above: Incorrect because loopback plugs are standard. Common Pitfalls: Using the wrong pinout; forgetting to configure baud/handshake; misinterpreting driver issues as hardware failures. Final Answer: loop backs (wrap plugs)

Question 19

Printer features: Which component enables an office printer to automatically print on both sides of the paper (duplex printing)?

Accepted Answer

Introduction / Context: Duplex printing saves paper by printing on both sides automatically. Identifying the printer subsystem responsible for flipping or re-feeding sheets is a common certification and support question. Given Data / Assumptions: We are discussing standard office laser/inkjet printers. Goal: automatic two-sided printing without manual page re-insertion. Mechanical modules add or route media during the print path. Concept / Approach: The duplexer is a mechanical module that reverses and re-feeds the paper so the device can print the second side. It may be internal or an external accessory. Other subsystems, such as the fuser and toner cartridge, handle image formation and fixing—not sheet inversion. Step-by-Step Solution: Identify the function needed: flip a printed sheet and re-insert for side two.Map that function to the duplexer module in the paper path.Select “duplexer” as the component that enables automatic two-sided printing. Verification / Alternative check: Printer specs list “auto duplex” or “duplexer included/optional.” Enabling duplex in driver settings works only when the hardware duplexer is present and configured. Why Other Options Are Wrong: Fuser: Heats and bonds toner; does not flip pages. Toner cartridge: Supplies toner; no page inversion role. Paper-swapping unit: Not a standard term; duplexer is the correct name. None of the above: Incorrect because duplexer is correct. Common Pitfalls: Confusing manual duplex (user flips) with automatic duplex; assuming driver setting alone guarantees duplexing without the hardware module. Final Answer: duplexer

Question 20

Computer buses: IBM’s Micro Channel Architecture (MCA) specified which data-path widths?

Accepted Answer

Introduction / Context: Understanding historical PC buses helps when supporting legacy equipment or studying for hardware certifications. IBM introduced Micro Channel Architecture (MCA) as a successor to ISA, with different electrical and configuration characteristics. Given Data / Assumptions: MCA is being compared by its data width capability. Common bus widths historically include 8, 16, 32, and later 64 bits. We focus on IBM’s MCA specifications, not EISA or PCI. Concept / Approach: MCA boards and slots came in 16-bit and 32-bit varieties. The 32-bit flavor supported higher throughput and bus mastering, differentiating MCA from ISA (8/16-bit) and EISA (32-bit) in design and licensing. Therefore, the correct pair is 16 bit & 32 bit. Step-by-Step Solution: Recall ISA widths (8/16) and PCI later (32/64) to avoid confusion.Identify MCA as 16-bit and 32-bit capable.Select “16 bit & 32 bit.” Verification / Alternative check: IBM PS/2 technical references list MCA models and expansion cards with both 16-bit and 32-bit implementations, confirming the specification. Why Other Options Are Wrong: 8 & 16: Matches ISA legacy, not MCA. 16 & 24: Not a common PC bus width pairing. 32 & 64: Matches later PCI derivatives, not MCA era. None of the above: Incorrect because 16 & 32 is correct. Common Pitfalls: Confusing MCA with EISA or PCI; assuming wider always means newer across all vendors without checking the bus family. Final Answer: 16 bit & 32 bit

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