3.5.11. Casing of PC Computer

All computer components are accommodated in a casing that may seem like a mere detail. But realistically speaking, CASE and POWER supplies have a very important role in the computer, especially for the newer computer systems that require a lot more energy resources than its predecessor designed a few years back. PC enclosure is in the individual elements is very strict of a standard so that is exactly what must be fixed spacing on the rear of the chassis between the actuator installed card, what is the minimum height in relation to the motherboard, so they can be distributed to holders motherboard inside and so on, and where the holes for the screws in the casing of the power supply. Today's casing design that can accept a standard ATX-2 motherboards in full (full) or abbreviated (micro) version. The back side is almost completely in all similar, and manufacturers have more freedom in the design of the facade and interior of the disk, and optical systems or the like. Offered is a newer standard called BTX, layout elements, which allows efficient cooling of components, but did not yet have a larger market share.

Cases can be divided into three basic groups:

desktop (desktop, horizontal standard height)
tower (upright, vertical standard width)
slim (narrower and smaller horizontal or vertical case)

The arrangement of elements within the first two mentioned types of case is almost the same so that a desktop enclosure and processed based on the vertical casing. The exception are the 'slim' small case height (low profile - half height) is called barebone (bare bone), intended only for the most essential component to say 'Mini-ITX' motherboard, but they are very non-standard forms. This case should 'accommodate' and BTX motherboards. Upright cases are currently the most widely used offerings. Inside of one little processed 'desktop' PC system is shown in the following Figure.

Figure**** 3.5.94 Inside case of desktop PC / Cooling process. ( + / - )

Upright casing is manufactured in many sizes and shapes. Common names for different frame sizes and their standard features available in the market are:

Micro tower
One place to optical device, one or two of the hard drive. Designed for the 'barebone' systems (which typically distribute brand-name manufacturers) or Mini-ITX size motherboard. It is especially suitable for office use where space occupied by a computer should be as small as possible.
Mini tower
Two positions for optical devices, two of the hard drives and the place of the floppy disk drive. Accepts all size ATX motherboards, but when you use a full-size ATX board could occur in crowded case.
Midi tower
Three or four places for optical drives, two to four seats for hard disks and place of the floppy disk drive. Best casing, if the space is not of paramount importance. With the high quality power supply that's part of that should be put up because it is a time-tested investment.
Big tower
Case for demanding users. There are five or more places for optical drives, and five more places for hard drives, two of the floppy disk drive or a nonstandard device as DAT or ZIP drive, memory card reader and so on.
Home Theather
The desktop or slim case, mostly horizontal, can accept ATX motherboards and has multimedia-specific accessories. They are generally more beautifully designed than desktop PC cases. They are characterized by high air permeability of the case so that cooling would be efficient at low speed of large side fans, and thus achieve very quiet operation.

Figure**** 3.5.95 Case for Home Theather. ( + / - )

Once again it should be noted that one of the parts of the case depends largely stable operation of computers and long life embedded components - POWER supplies. Should be repeated, and that is a serious problem and maintain acceptable working TEMPERATURE inside the computer, and to ensure good ventilation as shown in the previous picture.

The author of these lines really liked the very airy case for Micro-ATX and Mini-ITX motherboards. There is nothing that cannot be incorporated into it. It is very affordable to install components although it seems a bit chunky. It is decorated primarily with the possibility of installing two 140 mm fans, one 120 mm fan and an accessible dust filter on the upper side of the case. The PSU with its fan takes air from below, of course with an easily accessible dust filter. So the air flow through the case is very good.

Figure 3.5.96 Very airy Micro-ATX case from the company 'Chieftec'.

Compact m-ATX cube format. Despite its very compact dimensions, this case is extremely flexible in terms of hardware compatibility, supporting ATX PSU’s up to 160 mm in length, graphics cards up to 320 mm in length and CPU coolers up to 160 mm in height. Additionally, with lots of exibility on the internal and external drives, supporting 5.25" and 3.5" optical drives, 2 x 3.5" HDD's and 3 x 2.5" SSD's, the case is also very suitable for home entertainment purposes or as a mini server.

The descriptions should not be confused with professional enclosures for servers, although it would be of big tower could make one server. Specificity of server case, in addition to the items listed in Chapter 3.3.9, is the fact that some are made in 19" 'rack' version for installation in cabinets (rack-this) to make it easier to realize a unique computer system of a multitude of functionally linked server - CLUSTER.

To make the device built into the casing they need to do is some kind of interconnect cables and connected to a power source (power supply). Inside the casing there are two main groups of connection cables:

SIGNAL - cables that connect devices to the motherboard or the devices.
PSU - cables that connect the motherboard and devices to a power source.

PATA devices connect FLAT signal cable with 40 or 80 lines, depending on whether or not a unified mass. In ATA (PATA) standard each channel supports one primary and one secondary device in that sense one of the devices on the channel using jumper is declared for the main (MASTER) and the other for additional (SLAVE). In a similar way to connect devices and disk but the choice of primary and secondary unit by twisting a couple of lines between the two cable connectors to accomplish certain functions on a pin-on connectors. This group uses a 4 pin device-ment supply cables and connectors. SATA standard does not require setup disk and optical devices jumper. Application SATA devices involves different signaling and power cables and connectors, basically a lot less lines, signal cable with 7 lines and power cable with 5 lines, provided that the individual lines using more pins connector. SATA power cable in relation to the PATA cable, provides an additional line through which the power supply to provide from 3.3 V for devices that require lower power. Connectors power source for PATA and SATA devices are not the same and care must be taken when changing the motherboard and hard drive. They will certainly need to change the source of supply. Specificity in this respect are the cables for USB and IEEE 1394 connector connector with power supply and signal lines, cables, fans, or other special purpose cables.

Miniaturization of computer components and thin LCD monitors has led to a new category of PCs - All-In-One. All computer components are built into the monitor and enable entirely comfortable work for not demanding computer users. Of course advanced computer upgrade is not provided. Very useful design computers for companies with lots of employees and typified activity, as firms like 'sales' of any such computer to work in sales or POS-PC.

SET-UP sustava - BIOS

Setting the initial parameters, is an integral part of the ROM BIOS of the computer. Usually activated by pressing <DEL>, <F2> or a combination of the <CTRL> + <ALT> + <ESC>. Usually the opening screen when turning on the computer states that action to a particular key or key combination to access SETUP-in (setting) the BIOS, and if not stated anywhere, certainly explained in the instructions that were submitted to the motherboard. Data to be written this way are placed in a small additional memory (CMOS or similar), to which the content is kept constant by maintaining power with a built small battery. The basic options that can be set using the SET-UP program in the BIOS data for:

      1. date                          7. secondary (disk-optical) device [E:]
      2. time                          8. secondary (disk-optical) device [F:]
      3. floppy device [A:]            9. video parameters
      4. floppy device [B:]           10. conventional memory
      5. primary disk drive [C:]      11. memory expansion
      6. primary (disk) device [D:]   12. remaining parameters

Mentioned are only the basic options, and the remaining options relate to the memory banks, cache memory, bus speed, the order of appearance of disk devices and by the inclusion of a second and even a protective surveillance programs write to the boot sectors of the disk. All these options are described in detail in the instructions that came with the PC's motherboard, where all menus are described in the BIOS and change the way certain facilities, and one possible design menu is shown in Figure 4.5.5d. Due to the different speed of data access is well-disk devices connected to the system through a single channel, and through the other optical devices. If you want to connect more than four PATA devices should be mounted in the form of embedded controller cards, which may contain support for RAID system. PATA architecture is basically a bus architecture, which involves the interaction between the device and the slower device may affect the performance of faster devices if they are on the same bus.

SATA controllers for each device to be served by having a separate access electronics and appliances are connected to a separate controller cable. Typically shipped motherboards with 4 or 8 SATA ports. No interaction between devices. In addition to the above almost all SATA RAID controllers have the support of home computers is not fully hardware but rather relies on the driver incorporated in the OS, a separate program that is usually supplied on a floppy disk that can be attached and OS installation if necessary (key <F6> for Windows XP for example). Among those devices are no interactions. Compatibility with SAS (Serial Attached SCSI) technology is another very good feature SATA conception. SATA technology involves the use of NCQ (Native Command Queuing) technology regarding the acceleration of reading data from a disk device.

When setting the BIOS, some attached devices BIOS software routines themselves recognize, and some need to be set at the discretion. The data are subject to changes recorded in the CMOS memory of the BIOS to remember them as long as it is live. Specifically BIOS reads the records stored in the CMOS memory belonged to him, which are nothing else than - instruction for BIOS, parameters to which component of the system should work and how to access it. If the parameters are not in line with what the BIOS expects, either due to incompatibility or defective components, there will be a fault in the system, and in the worst cases, failure of computer systems. So, the BIOS allows you to change tracks in CMOS memory belonged to him, and special programs can be made to change the content (versions) BIOS.

How to program routines BIOS partly rely on the information kept in his memory, and CMOS, which basically represent somewhat variable parameters, it is possible to change their values by the user within certain limits, which allows for example increasing operating frequency bus , microprocessors and similar assemblies or individual parts working voltage in relation to the declared value. Sequence is an increase in system performance with increasing TEMERATURE of components such as side effects which include at least their better cooling. This process is called OVERCLOCKING, but if you overdo it can be ruinous regarding proper computer circuits. In view of the above, the modern BIOS is relies on a quite large its own FLASH memory in which everything can be 'injected' and uses fairly large CMOS memory, including, for example, the control of the fan speed in the case, as shown in the following Figure.

Figure 3.5.97 BIOS settings for fans of case.

The initial implementation of BIOS and CMOS memory of his power were resolved with a small battery pack that is the work of a computer during the filler and supplied the BIOS and CMOS memory power a few weeks in case of shutdown. Today it is more popular button-LITHIUM BATTERY (coin-cell battery); diameter 20.0 mm, height 3.2 mm, voltage 3 V, 220 mAh capacity, type CR2032. The solution is cheap, but it has the disadvantage that the battery is not being charged and so after a few years must be replaced as they lose their contents entered into the CMOS memory, BIOS, and the computer can get confused during the POST (Power On Self Test) process or in full 'fit' although the hardware device correctly. Better BIOS will signal the user that the battery is low.

BIOS based on FLASH (FLASHROM) memory differs from its CMOS memory in that it is dedicated programming support to write content in its flash memory if power supply is not lost nor can be lost or damaged. These are program routines that need to effectively connect all devices computers. Sometimes it is used instead of the classic FLASH ROM memory and updates the BIOS and change the contents were not possible. Motherboard manufacturers usually over the Internet be able to download a new version of the BIOS for your product, as well as utilities to upgrade the BIOS. In this, and recognize a reputable manufacturer and a quality product. Intel motherboard for D945GNT of 09.05.2005. to 11.09.2006. issued 37 content revisions of BIOS, with a very easy and affordable to upgrade.

BIOS upgrades are necessary, especially if recently produced a motherboard upgrade-able to support newer versions of microprocessors. From design to production, packaging and distribution of a large number of motherboards pass some time, and has built versions of the BIOS and certainly some of the basic version, and one can not expect the manufacturer to withdraw the product from the market regarding the upgrade. That part must be done by user, and if on the Internet does not exists support to perform an upgrade for a motherboard, that motherboard does not need to buy. Should ensure that in the process of upgrading the BIOS and the computer is not left without power supplies (UPS), as it may cause damage to the records and hence the uselessness of computers.

Characteristics embedded in the BIOS are different for various manufacturers, and if it is not necessarily needed some micro software routines and the organization of long BIOS does not change. So are closely related to the ability of the BIOS settings hard disk and operating system, and the limits of the maximum possible value of the partition eventually changed any BIOS upgrade or redesign its subsequent revisions in the motherboard or in the design of new motherboards. Some standard features for a long time does not change, so it is still possible to directly retrieve four partitions on the hard disk to entries the BIOS, no matter how many discs there. Hence the restriction of a maximum of FOUR PRIMARY partitions, in case you need more partitions on one of the partitions will be declared in Extended (expanded) which can be divided into a much more logical parts, because one can notice the logical partitions in the BIOS but not in the initial blocks EXTENDED partition as an extension records in the BIOS, as noted in the description on the site in Chapters 3.5.5, 4.3.1 i 4.4.2 and in Appendix i.). The basic difference between primary and extended partitions is that only primary disk partitions can be just starting, (bootable).