A+ Core (220-301) hardware Technologies  -ExamCram

Exam cram notes:

1. Some important acronyms:

• ISA is an acronym for Industry Standard Architecture,
• EISA is a acronym for Extended Industry Standard Architecture,
• PCI is an acronym for Peripheral Component Interconnect, and
• MCA stands for Micro Channel Architecture.
• CPU stands for Central Processing Unit.
• SCSI stands for Small Computers Systems Interface. It is pronounced as Skuzzy.
• DIMM stands for Dual-Inline Memory Module
• SIMM stands for Single-Inline Memory Module
• SRAM - Static random access memory - Uses transistors to store information
• DRAM - Dynamic random access memory - Need to be refreshed to retain data.
• ROM - Read only memory - Data in ROM can not be erased or changed
• PROM - Programmable ROM - Once programmed, data can't be erased or changed
• EPROM - Erasable PROM - Data can be erased by ultraviolet light and can be  reprogrammed using a programmer.
• EEPROM - Electronically erasable PROM - Data can be erased electrically. Chip can then be reprogrammed. EEPROMs are frequently used to store BIOS.

2. RAM stands for Random Access Memory. There are basically two types of RAM:

1.      DRAM - Dynamic RAM, and

 2.      SRAM - Static RAM.

SRAM, being expensive, usually used for Cache memory. DRAM, being cheaper, is used for main memory.

3. PC Memory cards:

·        A SIMM  has a single row of 72 contact fingers, each making contact on both sides (Same pin number present on both sides of the card). An older version of SIMM card contain 30pins, and were used in 386 and some 486 machines.

·        A DIMM (Dual-Inline Memory Module)has two rows of connecting fingers, one row on each side, and the total number of contacts are 168 contacts.

4. Monitor Connectors:

·         If you are using a Monochrome / CGA/ EGA monitor, it is a digital monitor and will have a DB-9 Male connector that plugs into a digital adapter.

·         If you are using a VGA/ SVGA monitor, it will have a male DB-15 connector that plugs into an analog adapter. You should never interchange an analog monitor to that of a digital adapter and vice versa, or severe damage may take place.

5. The storage capacity of various types of floppy:

Size------Type----Storage

5 1/4" ---DSHD----1.2MB

3 1/2" ---DSDD----720KB

3 1/2" ---DSHD----1.44MB

3 1/2" ---DSED----2.88MB

DSDD: Double Sided Double Density

DSHD: Double Sided High Density

DSED: Double Sided Extra Density

7. Video types:

The table below compares various video types:

Video monitor	Max. Color depth	Max. Resolution
CGA	16 Colors	160X100
EGA	64 colors	640X350 (Graphics Mode)
VGA	256 colors	640X480 (Graphics Mode)
SVGA	16 Million Colors	1280X1024 or even more

8. When you are changing a video monitor on a PC (say, during troubleshooting):

When you are installing a different SVGA monitor, it is likely that the new monitor has the same capabilities as the old one. As a result, the image on the screen may not be readable. In such instances, change the video resolution to Standard VGA before installing the new monitor. You can change the resolution appropriately after the image on the screen is readable with the new monitor. It may also be necessary to load appropriate device driver, if you are installing a different display adapter.

9. FAT file system:

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.

10. Real Time Clock:

The Complementary Metal-Oxide Semiconductor (CMOS) allows the computer to store the Real Time Clock (RTC)and other device information even after the computer is switched off and on. This is achieved by using a battery back, just for CMOS.