Exam notes for A+ Core 1

Exam notes

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20. Tools - Screw driver types:

21. Most commonly used modem commands:

22. General PC error codes and probable causes:

Some of the frequently encountered error codes and their corresponding error messages are given below:

Error Code

Error Message

161

CMOS battery failure: Replace the CMOS battery

164

Memory size error : If the error occurs after memory upgrade, run SETUP program.

201

Memory test failed : RAM chips failed, one or more may need to be replace.

301

Keyboard error: You may have to check the key board

23. Cable lengths:

24. When communicating across a serial cable, the most probable cause that the screen is dumping garbled characters is that the communication settings are not correct. Check the speed, parity, start/stop bits etc. If this is all correct, then you need to check the cable. Check whether you need a straight / cross cable, and the pin connections.

25. Power On Self Test (POST) happens after the computer cold boots.

6. The following devices require periodic cleaning:

27. Monitors and static charge:

1. Monitors accumulate very high static charges and need to be handled very carefully. Before attempting any repair, it is important to discharge any accumulated charges on the monitor. You can use a jumper, one end of which is grounded, and touch the other end of the jumper wire to the anode of the monitor. While doing so, ensure that you are not in direct contact with the jumper wire or the anode. You can use a screwdriver, or a nose pliers with rubber handle for this purpose. A "POP" sound can be heard when the static charges accumulated on the anode lead getting grounded through the jumper wire. Static charges accumulated on monitors may lead to severe burn or even fatal, if come into direct contact.

2. Never wear a wrist strap when working on monitors. Monitors contain very high voltages, sometimes fatal to human, even when the power is turned off. If you are wearing wrist strap, the human body works as a conduit to discharge the electric charge.

28. System board connectors of a PC:

29. MS –DEFRAG utility: To defragment the hard disk, you can run Microsoft defragment utility by issuing a command "DEFRAG".

30. ESD:

31. Uninterrupted Power Supply (UPS):

An UPS is desired to be purchased for any critical and un-interrupted use of computers. It has the following benefits:

Note that the UPS can give un-interrupted power only for a fixed amount of time under a given load, in the absence of line voltage.

32. The following are types of PCMCIA (PC cards) cards:

33. Computer Cache Memory: Level 1 cache is internal to the processor, and level 2 cache is external to the processor, it resides on the motherboard. In case of Pentium II, L2 cache is built into the cartridge.

34. CPUs and features:

Processor

Socket type

Register

Data Bus

Address Bus

8088

DIP

16 bit

8 bit

20 bit

80286

LLC/PGA/PLCC

16 bit

16 bit

24 bit

80386SX

PGA

32 bit

16 bit

24 bit

80386DX

PGA

32 bit

32 bit

32 bit

80486SX

PGA

32 bit

32 bit

32 bit

80486DX

PGA/SQFP

32 bit

32 bit

32 bit

Pentium

Socket 5 SPGA/ Socket 7 SPGA.

64 bit

64 bit

32 bit

Pentium Pro

Socket 8 SPGA

64 bit

64 bit

32 bit

Pentium II

SEC Slot 1

Pentium III

SECC-2 / PPGA or FC-PGA

Pentium IV

socket 423/socket 478/ socket 775

64 bit

64 bit

36 bit*

Pentium Dual Core

Socket 775 (LGA775)

64 bit

64 bit

64 bit*

Pentium Quad Core

Socket 775 (LGA775)

64 bit

64 bit

64 bit*

* 32-bit operating systems like Windows XP can support only 32 bits of addressing space, and hence only 4GB of memory can be used. By using 64-bit operating systems, 16 Exa bytes (EB) of RAM can be used. 36 bits of address space can access up to 64GB of memory.

CPU models 80486SX, and above contain on board cache memory.

35. Bits and Bytes:

1 KB = 1024 bytes
1 MB = (1024 X 1024) bytes 
= (1024X 1 KB) bytes 
= 1,048,576 bytes 
1 GB = (1024 X 1024 X 1024 )bytes 
= (1024 X 1 MB) bytes 
= (1024 X 1024 X 1 KB) bytes 
= 1,073,741,824 bytes 
KB stands for Kilobyte 
MB stands for Megabyte 
GB stands for Gigabyte 
Byte is represented by "B" as in MB 
Bit is represented by "b" as in kbps 
One byte is 8 bits
		

36. Printer parallel ports come in the following varieties:

37. Laser printers:

The following are the 6 steps in the ElectroPhotographic (EP) print process of Laser Printer:

Some of the frequently encountered problems using laser printers and probable causes are as given below:

38. Impact printers are capable of printing multipart forms, since they can give necessary impression to print to multiple forms simultaneously. ECP (Extended Capability Port) has less control overhead and best suited for transferring large chunks of data, such as between the computer and laser printer.

39. The interface cables used widely have the following pin count:

40. One good way of determining a bad power supply is that the fan will not rotate. Also, the computer will not boot and the LED s indicating the speed will be OFF.

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