Computer Science, Chapter 1

Southbridge

Allows the CPU to communicate with slower speed devices including hard drives, Universal Serial Bus (USB) ports, and expansion slots.

read-only memory (ROM)

An essential computer chip is the read-only memory (ROM) chip. Rom chips are located on the motherboard and other circuit boards and contain instructions that can be directly accessed by a CPU. The instructions such as booting the computer and loading the operation system. ROM is nonvolatile which means that the contents are not erased when the computer is powered off.

Basic input/output system (BIOS) chip and Unified Extensible Firmware Interface (UEFI) chip

BIOS is used to help boot the computer and manage the flow of data between the hard drive, video card, keyboard, mouse, and more. Recently the BIOS has been enhanced by UEFI. UEFI specifies a different software interface for boot and runtime services but still relies on the traditional BIOS for system configuration, power-on self -test (POST), and setup.

Berg Keyed Connector

Connect to legacy floppy drives. Smaller than a Molex connector

6/8-pin PCIe Power Connector

Connector has two rows of three to four pins and supplies power to internal components.

4-pin to 8-pin Auxiliary Power Connector

Connector has two rows of two to four pins and supplies power to different areas of the motherboard. The auxiliary power connector is the same shape as the main power connector but smaller.

SATA Keyed Connector

Connects disk drives. Connector is wider and thinner than a Molex connector.

Molex Keyed Connector

Connects hard drives, optical drives, or other devices.

20-pin or 24-pin

Connects to the motherboard. The 24-pin connector has two rows of 12-pins each. The 20-pin connector has two rows of 10-pins each.

Northbridge

Controls high speed access to the RAM and video card. It also controls the speed at which the CPU communicates with all of the other components in the computer. Video capability is sometimes integrated into the Northbridge.

DDR SDRAM (Double Data Rate Synchronous Dynamic RAM)

DDR SDRAM transfers data twice as fast as SDRAM. Able to support two writes and two reads per CPU clock cycle. Connector has 84-pins and a single notch. Uses lower standard voltage (2.5 v). Family: DDR2, DDR3, DDR4.

DDR2 SDRAM

DDR2 SDRAM also transfers data twice as fast as SDRAM. Runs at higher clock speeds than DDR (553 MHz vs. DDR at 200 MHz). Improves performance by decreasing noise and cross-talk between signal wires. Connector has 240-pins. Uses lower standard voltage (1.8 v).

DDR4 SDRAM

DDR4 SDRAM quadruples DDR3 maximum storage capacity. Consumes less power than DDR3 (1.2 v). Runs at higher clock speeds up to 1600 MHz. Connector has 288-pins. Available with advanced error correction features such as error-correcting code memory (ECC memory) to detect multiple bit errors.

SDRAM (Synchronous Dynamic RAM)

DRAM that operates in synchronization with the memory bus. Able to process overlapping instructions in parallel-e.g. It can process a read before a write has been completes. Higher transfer rates.

EPROM (type of ROM)

Erasable programmable read-only memory in non-volatile but can be erased by exposing it to strong ultraviolet light. EPROMs usually have a transparent quartz window on top of the chip. Constant erasing and reprogramming could ultimately render the chip useless.

Pin Grid Array (PGA)

In PGA architecture, the pins are on the underside of the processor package and is inserted into the motherboard CPU socket using zero insertion force (ZIF). ZIF refers to the amount of force needed to install a CPU into the motherboard socket or slot.

Land Grid Array (LGA)

In an LGA architecture, the pins are in the socket instead of on the processor.

EEPROM (type of ROM)

Information is written to an electrically erasable programmable read-only memory chip after it is manufactured and without removing it from the device. EEPROM chips are also called Flash ROMs since its comtents can be "flashed" for deletion. EEPROMs are often used to store a computer system's BIOS.

PROM (type of ROM)

Information on a programmable read-only memory chip is written after it is manufactured. PROMs are manufactured blank and then can be programmed by a PROM programmer when needed. Generally, these chips cannot be erased and can only be programmed once.

Dynamic RAM (DRAM)

Older technology, popular until the mid-1990s. Used for main memory. DRAM gradually discharges energy so it must be constantly refreshed with pulses of electricity order to maintain the stored data in chip.

Random Access Memory (RAM)

RAM is the temporary working storage foe data and programs that are being accessed by the CPU. Unlike ROM, RAM is volatile memory, which means that the contents are erased every time the computer is powered off. Adding more RAM in a computer enhances the system performance. For instance, more RAM increases the memory capacity of the computer to hold and process programs and files. With less RAM, a computer must swap data between RAM and the much slower hard drive. The maximum amount of RAM that can be installed is limited by the motherboard.

Static RAM (SRAM)

Requires constant power to function. Often used for cache memory. Uses lower power consumption. Much faster than DRAM. More expensive than DRAM.

GDDR SDRAM

The "G" stands for Graphics. RAM is specifically designed for video graphics.

ITX

The ITX form factor has gained in popularity because of its very small size. There are many types of ITX motherboards; however, Mini-ITX is one of the most popular. The Mini-ITX form factor uses very little power, so fans are not needed to keep it cool. A Mini-ITX motherboard has only one PCI slot for expansion cards. A computer based on a Mini-ITX form factor can be used in places where it is inconvenient to have a large or noisy computer.

Central Processing Unit (CPU)

The central processing unit (CPU) is responsible for interpreting and executing commands. It handles instructions from the computer's other hardware, such as a keyboard, and software. The CPU interprets the instructions and outputs the information to the monitor or performs the requested tasks. The CPU is a small microchip that resides within a CPU package. The CPU package is often referred to as the CPU. CPU packages come in different form factors, each style requiring a particular socket on the motherboard. Common CPU manufacturers include Intel and AMD. The CPU socket is the connection between the motherboard and the processor. Considered as the brain of the computer.

Power Supply Voltage

The different connectors also provide different voltages. The most common voltages supplied are 3.3 volts, 5 volts, and 12 volts. The 3.3 volt and 5 volt supplies are typically used by digital circuits, while the 12 volt supply is used to run motors in disk drives and fans. Power supplies can also be single rail, dual rail, or multi rail. A rail is the printed circuit board (PCB) inside the power supply to which the external cables are connected. A single rail has all of the connectors connected to the same PCB while a multi rail PCB has separate PCBs for each connector. A computer can tolerate slight fluctuations in power, but a significant deviation can cause the power supply to fail.

Cooling Systems

The flow of current between electronic components generates heat. Computer components perform better when kept cool. If the heat is not removed, the computer may run more slowly. If too much heat builds up, the computer could crash, or components can be damaged. Therefore, it is imperative that computers be kept cool. Computers are kept cool using active and passive cooling solutions. Active solutions require power while passive solutions do not. Passive solutions for cooling usually involve reducing the speed at which a component is operating or adding heat sinks to computer chips. A case fan is considered as active cooling.

Form Factor

The form factor of motherboards pertains to the size and shape of the board. It also describes the physical layout of the different components and devices on the motherboard. There have been many variations of motherboards developed over the years.

Motherboards

The motherboard, also known as the system board or the main board, is the backbone of the computer. As shown in the figure, a motherboard is a printed circuit board (PCB) that contains buses, or electrical pathways, that interconnect electronic components. These components may be soldered directly to the motherboard, or added using sockets, expansion slots, and ports.

Expansion slots

These provide locations to connect additional components.

Chipset

This consists of the integrated circuits on the motherboard that control how system hardware interacts with the CPU and motherboard. It also establishes how much memory can be added to a motherboard and the type of connectors on the motherboard.

Micro-ATX

This is a smaller form factor that is designed to be backward-compatible with ATX. Micro-ATX boards often use the same Northbridge and Southbridge chipsets and power connectors as full-size ATX boards and therefore can use many of the same components. Generally, Micro-ATX boards can fit in standard ATX cases. However, Micro-ATX motherboards are much smaller than ATX motherboards and have fewer expansion slots.

Advanced Technology eXtended (ATX)

This is the most common motherboard form factor. The ATX case accommodates the integrated I/O ports on the standard ATX motherboard. The ATX power supply connects to the motherboard via a single 20-pin connector.