CompTIA® A+™ Exam Notes : Differentiate Among Various Cpu Types And Features
8. SCSI Types
8 bit bus
Fast Wide SCSI
16 bit bus
Wide Ultra SCSI
16 bit bus
8 bit bus
Wide Ultra2 SCSI
16 bit bus
Ultra3 SCSI or Ultra 160
16 bit bus
16 bit bus
SCSI ID - 0=bootable drive, 7=controller, 1-6=any other devices Wide-Ultra SCSI - 16 devices, 0=bootable drive, 15=controller
Each device in a SCSI chain need to have unique ID. For a 16-bit Wide SCSI, there are 16 possible SCSI Ids, 0-15. A standard 8-bit SCSI can support only 8 devices (including SCSI card), the Ids allowed are 0-7.
SCSI bus termination: If the termination is not done, a SCSI devices on the bus will not function properly. This is due to reflection of the signals at the end of the bus. To prevent this, both ends of the SCSI bus need to be terminated. If one end of the SCSI bus is terminated, you may find intermittent problems. Never terminate the bus at a device connected in between.
9. USB (Universal Serial Bus):
a. USB supports up to 127 devices simultaneously.
b. USB enables you to daisy chain up to 127 USB devices. A USB hub is used for this purpose.
c. USB devices can be plugged in without turning on/off power. i.e, USB devices are hot swappable.
d. The important features of USB 2.0 are given below:
1. Mbit/s 12Mbit/s 480Mbit/s supported.
2. USB controller is required to control the bus and data transfer.
3. Cable up to 5 m.
4. Up to 127 devices supported.
5. Power supply to external devices is 500 mA/5V (max).
6.Full compatibility with USB 1.1 devices.
e. To achieve proper USB connectivity six basic system elements must be present
1. Support from the BIOS
2. Support from the Operating System
3. Physical USB ports
4. A USB Device
5. The correct USB cable for the device
6. Drivers either from the OS and/or the peripheral maker
f. USB 2.0 has a raw data rate at 480Mbps, and it is rated 40 times faster than its predecessor interface, USB 1.1, which has 12Mbps max speed.
a. External Serial Advanced Technology Attachment or eSATA is an external interface for SATA technologies. It is faster compared to USB 2.0 or PATA technologies, and suitable for backing up large amounts of data using external hard drive.
b. Even though eSATA is part of the SATA interface specifications, it uses a very different physical connector from the internal SATA connectors. The reason for this is to better shield the high speed serial lines used to transfer the signals from EMI protection. It also provides a 2m overall cable length compared to the 1m for internal cables. As a result the, the two cable types can not be used interchangeably.
c. eSATA is hot swappable. Other drives IDE, EIDE, AND PATA does not support hot swap.
a. Storage capacity of blue-ray: 25GB (single-layer) and 50GB (dual-layer)
b. Blue-ray drives are usually compatible with CD/DVD drives, but not the other way round.
12. SSD (Solid State Drives) access data stored in the drive using direct access. Since there are no mechanical rotating components that are found in conventional hard drives, the data access would be much faster.
1.6 Differentiate among various CPU types and features and select the appropriate cooling method
1. Processor package types:
a. 8088, 8086 processors used 40 pin DIPs. 80286,80386, 80486, and some Pentium computers (60MHz, 66MHz) used PGA (Pin Grid Array).
b. Pentium chips (75 MHz and above) used SPGA (Staggered PGA). Pentium II CPUs use catridge type mounting method, called "slot-1".
CPUs and features:
Socket 5 SPGA/ Socket 7 SPGA.
Socket 8 SPGA
SEC Slot 1
SECC-2 / PPGA or FC-PGA
socket 423/socket 478/ socket 775
Pentium Dual Core
Socket 775 (LGA775)
Pentium Quad Core
Socket 775 (LGA775)
c. 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.
d. CPU models 80486SX, and above contain on board cache memory.
Address Bus Size
16 EB (Exa Bytes)
e. A computer may reboot because of CPU overheating. Ensure that you have sufficient ventilation for proper airflow, and that the CPU fan is working.
a. It is an Intel invention for their processor cores that allows the CPU to present the Operating System with two "virtual" CPUs, each with its own set of resources. This new technology allows multiple processing threads to run in parallel on a single chip. The Operating System and associated hardware need to support hyper-threading for using this feature. For each processor core that is physically present, the operating system addresses two virtual or logical cores, and shares the workload between them when possible. The main function of hyper-threading is to decrease the number of dependent instructions on the pipeline.
b. Requirements for the HT enabled system:
Intel Pentium 4 processor at 3.06 GHz or higher
An IntelÂ® chipset that supports HT Technology
System BIOS that supports HT Technology and has it enabled
An operating system that includes optimizations for HT Technology
c. Only Operating Systems Windows XP and above support Hyper-threading.
3. Bits and Bytes
1 KB = 1024 bytes
1 MB = (1024 X 1024) byte
= (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
The Slot 1 package replaces the Socket 7 and Socket 8 used by previous Pentium processors. Slot 1 is a 242-contact daughter card slot that accepts a microprocessor packaged as a Single Edge Contact (SEC) cartridge. A motherboard can have one or two Slot 1s. More recently, Slot 2 package has been developed and used by recent processors.
4. File system
a. FAT :Under FAT file system, the maximum size of a cluster is 32 KB and the maximum number of clusters is 65536. Therefore, the maximum size of a partitions is the number of clusters multiplied by the max size of the cluster, which is equivalent to 2 GB. Remember that 1 KB = 1024 bytes.
b. NTFS: New Technology File System (NTFS) is a file system that was introduced by Microsoft to provide superior features like encryption, compression, and user permissions. NTFS is the primary file system used in Microsoft's Windows NT, Windows 2000, Windows XP, Windows 2003, Windows Vista, and Windows 7 operating systems.
c. You can't apply file level permissions on a FAT file system. Only NTFS allows file permissions. Remember that the NTFS file permissions are always in effect to all users and processes.
d. Windows 98 and Windows 95 OEM Release 2 support FAT32. Note that Windows NT does not support FAT32. NT supports only FAT16 and NTFS. Windows 2000 supports FAT16, FAT32, and NTFS.
e. DOS standard FAT16 support drives up to 2 GB. FAT32 supports drives up to 2TB (Terabytes).
a. Popular Intel socket types include LGA 1156/Socket H, LGA775, LGA 1155/1156, rPGA 988A, Socket G1, etc. Popular AMD socket types include LGA 940, Socket FM1, Socket AM3, Socket G34, etc.
b. Socket LGA775 motherboards run Intel's Celeron (single-core), Pentium 4 (single-core), Pentium D (dual-core) and Core 2 Duo (dual-core) desktop processors.
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