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Newbie Guides 
Beginners Corner
PC Hardware Reference
The PC hardware reference guide is in three parts.
PC Hardware Reference Guide - Part 1
Tutorial Quick Links:
Installation, Configuration and Upgrading
Diagnosing and Troubleshooting
Safety and Preventative Maintenance
Part 2
Motherboard, Processors and Memory
Printers
Part 3
Portable Systems
DOS and Windows
Installation, Configuration, and Upgrading
This section is concerned with the knowledge and skills to identify,
install, configure and upgrade microcomputer modules. Includes IRQ's,
DMA's and IO addresses.
IRQ Settings
IRQ 0 - System Timer
IRQ 1 - Keyboard
IRQ 2(9) - Video Card
IRQ 3 - COM2, COM4
IRQ 4 - COM1, COM3
IRQ 5 - Available (LPT2 or Sound Card)
IRQ 6 - Floppy Disk Controller
IRQ 7 - LPT1
IRQ 8 - Real-Time Clock
IRQ 9 - Redirected IRQ 2
IRQ 10 - Available
IRQ 11 - Available
IRQ 12 - PS/2 Mouse
IRQ 13 - Maths Co-Processor
IRQ 14 - Hard Disk Controller
IRQ 15 - Available
I/O Address Settings
1FO-1F8 - Hard Drive Controller, 16-bit ISA
200-20F - Game Control
210 - Game I/O
220 - Soundcard
278-27F - LPT2
2F8-2FF - COM2
320-32F - Hard Drive Controller, 8-bit ISA
378-37F - LPT1
3B0-3BF - Monochrome Graphics Adapter (MGA)
3D0-3DF - Colour Graphics Adapter (CGA)
3F0-3F7 - Floppy Controller
3F8-3FF - COM1
Serial Communication
Uses RS-232C standard with DB9 or DB25. Transmits data sequentially
over a single conductor either synchronously or asynchronously. The Primary
Synchronous Control Signals are:
- Serial Data Out (TxD) - Used to Transmit Data.
- Serial Data Receive (RxD) - Used to Receive Data.
- Data Terminal Ready (DTR) - Used to tell receiver that data is ready
to be sent. Connected to the DSR on the receiving hardware.
- Data Set Ready (DSR) - Used on the Receiver to indicate it is ready.
- System Ground - Ground Reference Voltage between two devices.
Parallel Communication
Transmits data over eight conductors in parallel. Signals are either
control signals or data signals. Control signals are used to synchronise
the devices (Handshaking).
Primary Parallel Control Signals
- Acknowledgement - Used to inform the transmitting device that data
was received and the receiver is ready for more.
- AutoFeed - Used to inform the printer to generate an auto line feed.
- Busy - Used to inform sender that receiver is busy.
- Error - Used by receiver to indicate an error.
- Init - Used by sender to initialise the receiver.
- Slct - Used by the receiver to ack a Slctln.
- SlctIn - Used by the sender to select a device.
- Strobe Asserted - Used by the receiver to inform that data is present
on the lines.
Types of Connectors
Connectors are either Male (Pins) or Female (sockets).
- DB9 - Trapezoid, Video display and Serial ports.
- DB25 - Trapezoid, Parallel and Serial ports.
- RJ-11 - Phone line, 4 Wires UTP.
- RJ-14 - Dual line phone jacks, Not Common.
- RJ-45 - Network Connectors, 8 Wire UTP
- PS2/MINI-DIN - PS/2 Mouse and Keyboards, % pins and one guider.
Serial Ports are Male on the PC (DB9 or DB25)
Parallel Ports are Female on the PC (DB25)
Video is Male on the PC (DB9)
Mini/DIN is Female on the PC (PS/2)
IDE Devices
Integrated Drive Electronics are controllers for Hard Drives, CD-ROMS
and any other compliant device. The Controller is on the device itself.
- IDE < 528 MB so EIDE (Enhanced) was developed.
- Uses 40 Pin Cables.
- Floppy uses 34 pin Cables.
- CMOS has to be aware of the set-up of any E/IDE devices.
- Normally two channels and only two devices can be on each channel.
Master/Slave
If more than one device is on a channel you have to set it to Master
or Slave operation. This determines which controller takes precedent.
This is set through jumpers.
SCSI Devices
Small Computer Systems Interface allows you to connect multiple devices
to one cable. The Card is the controller so it removes overhead from the
Drive itself and the CPU.
- SCSI-1 - 8 Bit Bus, DB-25 or Centronics-50, 5 MBps, Device 0 to 7
- SCSI-2
- Wide - 16 Bit Bus, Device 0 to 15
- Fast - 10 MBps, Device 0 to 7
- Fast-Wide - 16 Bit Bus, 20 MBps, Device 0 to 15
- SCSI-3 - 16 Bit Bus, 40 MBps, Device 0 to 15
PS/2 machines give priority to the lower numbered ports. Other machine
to the higher.
The adapter is always given the ID of 0 on PS/2 machines or ID 7 for most
others.
The first hard disk is ID 1 on PS/2 and ID 0 for most others.
CD-ROM devices are ID 3
Slower devices are given slower ID's.
Internal SCSI uses 50 pin ribbon connectors.
External cables are female DB-25, Centronics 50, mini-50, or mini-68.
Both ends of the cable must be terminated. Some devices have inbuilt termination
which can be set via jumpers.
BIOS
Basic Input-Output System contains the system settings for the computer.
These are stores on a memory chip located on the motherboard. The settings
are removed from BIOS when you turn the computer off, but are restored
from the CMOS at boot time. The CMOS is powered by the battery. (Complimentary
Metal Oxide Semi-Conductor).
Flash BIOS means that the BIOS can be upgraded via a software Flash Program
from the BIOS vendor.
Removable BIOS means that to Upgrade you have to physically remove and
replace the BIOS chip.
System Optimization
- Memory - Basically free up conventional memory between 0K and 640K.
You can Load DOS into the high memory area by adding the following line
to the CONFIG.SYS. DOS = HIGH. Another way to free up conventional memory
is to load TSR's into upper memory. To do this you must first load EMM386.EXE.
You can then use DEVICEHIGH and LOADHIGH.
- Hard Drives - Hard Drives become fragmented. De-Fragment them with
the DOS command DEFRAG.
- Cache Memory - To improve performance add more.
Notes
Never wear an electrostatic wrist strap when working near a monitor
Electricity comes into the house AC, Computers use DC
The DC current is fed to your computer in two forms +-5Vdc and +-12Vdc
Diagnosing and Troubleshooting
This section is concerned with the knowledge to diagnose and resolve
various FRU faults.
POST Audible/Visible Error Codes
The Power On Self Test happens every time you boot the computer. It
is used to diagnose system related problems that are found in hardware
or BIOS. Anything other than a single beep indicates a fault.
| Error Range |
Component |
| 100-199 |
System Board Problem |
| 200-299 |
Memory Error |
| 300-399 |
Keyboard Problem |
| 400-499 |
Video Problems, Monochrome |
| 500-599 |
Video problems, Colour |
| 600-699 |
Floppy Disk Errors |
| 1700-1799 |
Hard Disk Problems |
Common Error Codes
| Error Code |
Error Message |
Description |
| 161 |
CMOS Battery Failure |
CMOS Battery needs to be
replaced |
| 164 |
Memory Size Error |
Occurs after a memory upgrade |
| 201 |
Memory Test Failed |
One or more of the RAM
Chips failed |
| 301 |
Keyboard Did Not Respond |
Indication that the keyboard
may need cleaning |
| 303 |
Keyboard or System Unit
Error |
Indicates a bad keyboard
that needs to be replaced |
| 423 |
Parallel Port test failed |
Reported with Monochrome
adapters. Will need to replace the adapter. |
Safety & Preventive Maintenance
This section is concerned with preventive maintenance, safety and disposal
requirements.
Cleaning Liquid cleaning compounds such as isopopyl alcohol can
be used to clean contacts and read/write heads via a cleaning diskette.
Rubber knifes can be used to remove hardened residue. Do not use metal
knives.
Always vacuum out the case whenever you get the chance to reduce the build
up of dust and also static electricity.
Power Issues
Brownouts Momentary lapse in power.
Power Spike Huge Increase in power for a split second.
Power Surge Like a spike but lower power.
UPS
A UPS protects your PC from brownouts, spikes, surges and dirty current.
This is accomplished by several components in the UPS such as suppressers,
noise filters, and surge protectors.
Suppressers - Absorbs or blocks the spike and protects against surges.
Noise Filters - Noise caused by Electro-Magnetic Interference(EMI) is
reduced.
CRT
Monitors are high voltage components. Never wear an ESD wrist strap
when handling monitors.
To discharge a monitor, connect a wire around the screwdriver and ground
the wire. Use the screwdriver to prise the anode lead from the back of
the CRT.
Disposal Procedures:
- Batteries - Batteries should be disposed of in accordance with guidelines
issued for your region. Never through them in the household waste.
- Toner Kits - Toner cartridges are recyclable. Normally the vendor
will take these from you.
- Computers - Give away to charity or contact a specialist.
- Material Safety Data Sheet(MSDS) - These are white pages that contain
information on any substance that is deemed hazardous.
Electro-Static Discharge
This can cause catastrophic damage where the device is inoperable
or it can cause degradation in a component which may still perform.
Hidden ESD is a static discharge that you can not feel. You only feel
ESD above 30,000 volts however components can still be damaged below 30,000
volts. To protect against ESD you can use ant-static mats, bags and an
ESD wriststrap. You can ground the wrist strap to the earth pin on a wall
socket. Also remove all metallic jewelery. Humidity below 50% leads to
static.
These study notes were developed by Andrew Mason.
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