MGV Glossary of Terms

GLOSSARY OF TERMS

PC 100

The list below gives an overview of three PC SDRAM (PC-100) specifications as defined by Intel. Taken together the specifications define the PC-100 DIMM’s.

PC SDRAM Unbuffered DIMM specification (Revision 1.0, February 1998): This specification is the guideline for the DIMM design. This specification goes beyond the JEDEC mechanical form factor and pin out requirement. This specification defines the connections, component placements trace impedance, signal topologies and trace length requirements for designing and manufacturing PC-100 DIMMS.
PC SDRAM Specification (Version 1.51, November 1997): This specification defines the essential functionality of the SDRAM components to be used on the PC-100 DIMM’s.
PC SDRAM Serial Presence Detect (SPD) Specification (Revision 1.2A, December 1997): This specification defines the SPD electrical and Data Structure requirements for SDRAM DIMM’s.

SDRAM	Synchronous Dynamic Memory Memory chips that synchronize the signal input and output with the CPU clock. This results in time saving thus improving performance. Execution of commands and transmission of data is in sync with CPU clock. Althou the SDRAM’s are designed to JEDEC standard, slight differences in the interpretation of the specification and the test methodologies have made the interchangeability a concern. Chips were capable of 100 MHz system operation under ideal conditions, but due to timing differences in most PC’s they have limited operation to 66MHz. New PC100 SDRAM chips are designed to increase performance and comply with tightened ac timing margins, dc parameters, driver characteristics and layout rules. (See above INTEL PC100 specifications). Available in two and four internal memory banks per chip. The chips operate at 3.3V. Currently capable of up to 143MHz/sec bandwidth.

DDRAM	Double Data Random Access Memory
	Essentially doubles the data transfer rate from a DRAM chip to the main processor. This is one of the new standards that are supported by following manufacturers: Samsung, NEC, Hyundai, Texas Instruments, Toshiba, Mitsubishi, Hitachi and Fujitsu. Currently this new, DDR standard manufactured chips are considered an interim before actual implementation of RamBUS high-speed memory. The chips will operate at 3.3V. Capable of 200MHz/sec bandwidth. DDR DRAM has, with their design stages, advanced to the later stage of JEDEC committee approval process. Final standardization of DDR specification is expected soon. Because of its open architecture, similar pin-out and packaging the incorporation into memory module requires few changes.

SLDRAM	SyncLink Similar to SDRAM, but has eight internal memory banks. Uses both the rising and falling clock edge to transmit data and a return clock signal to help improve timing margins. Main supporters include Siemens Micron and Hyundai. The chips will operate at 2.5V. Capable of up to 800MHz/sec bandwidth. SLDRAM has received JEDEC approval for its packaging pinout specification and should appear for full committee vote later this year.
	Because of its open architecture, similar pin-out and packaging the incorporation into memory module requires few changes.
MDRAM	Multibank DRAM Internally uses 32 banks per megabyte. Will permit the chips to handle many overlapping transactions, thus maximizing the data bandwidth. One limitation is that they require short buses and that in turn, limits the number of memory chips to four. Somewhat limited for memory applications. Capable of up to 600MHz/sec.

RDRAM	RamBUS, Concurrent RamBUS, version of RDRAM is divided into four banks (two banks on the 16/18-bit version). This is the second-generation implementation that has many timing and feature improvements over RDRAM. New memory architecture capable of 600MHz. Direct RamBUS, version of RDRAM. Jointly developed by INTEL to better match the memory to the Pentium CPU and deliver roughly 3 times the effective bandwidth of SDRAM. Licensees that will produce the chips are Hitachi, LG Semicon, NEC, Toshiba, OKI, Fujitsu, Hyundai, Siemens, IBM, Texas Instruments, Micron, Mitsubishi….. This will be the first of the super-pipelined memories that offer multiple-transaction pipeline and conflict-free transaction interleaving to achieve a sustained performance of 800MHz/sec. Chips will be controlled by RamBUS access controller (RAC) which can support single DRDRAM interface or two Concurrent RDRAM interfaces. Chips will operate at 2.5V.
PEMM	Processor Enable Memory Module New variations on the memory module design implementing DSP processors. Developed by Texas Instruments and code named Basaya the module will work with Pentium II and have 168 pin and 144 pin DIMM module pin-out. The module performs as regular SDRAM module until a DSP call comes in. At that point a dedicated partition is established in the memory function which, since it circumvents the slower PCI bus, performs radically better than traditional architectures.

Comparison of Next-Generation of 64-Mbit DRAM’s
Parameter / Type	SDRAM	DDRAM	SLDRAM	Direct RAMBUS
Bandwidth	0.8 Gbytes/s	1.6Gbytes/s	1.6Gbytes/s	1.6Gbytes/s
Clock Frequency	100MHz	100MHz	200MHz	400MHz
Data-Transfer Frequency	100MHz	200MHz	400MHz	800MHz
Package	TSOP/DIMM	TSOP/DIMM	VSMP/DIMM	TBD
Application	Low end-high end	Midrange-high end	Midrange-high end	Low end-midrange

Adapter
A circuit board that converts signals from a specialized peripheral device to signals used by the computer and vice-versa.

Application Program
A computer program that you use for a particular kind of task, like word processing or data communications.

Base I/0 Address
The memory location that the computer uses to communicate with a device attached to it. Unless otherwise specified, each device installed in or attached to the computer uses its own unique 1/0 address.

Base Memory
Another name for conventional memory, the first 640KB of computer memory. Your computer does not need any special software to use base memory.

BIOS (Basic Input/Output System)
Software (independent of any operating system) built into the computer that communicates with the screen, keyboard, and other peripheral devices.

Bit
A single binary digit represented as either a 0 or a 1.

Bus
A communication channel carrying signalsps.om any device used by the system to another device. For example, data being transferred to and from a hard disk travels on a bus.

Byte
The basic unit of measure for computer memory. A character, such as a letter of the alphabet, uses one byte of memory. Computer memory is often measured in kilobytes or megabytes. Each byte is made up of eight bits.

CMOS (Complementary Metal-Oxide Semiconductor)
The memory that stores the configuration you establish by running the computer's setup program. CMOS memory uses very little power and stores the configuration information even when the computer is turned off.

Controller
A circuit that controls a peripheral component. A controller removes the burden of controlling the device from the microprocessor.

Conventional Memory
The first 640KB of (RAM) Random-Access Memory. Operating systems and application programs can access this memory directly without using memory management software. Conventional memory is also known as base memory.

Data
Information; represented within the computer as a series of binary digits.

DIMM (Dual In-line Memory Module)
A small printed circuit board that contains memory chips.

DMA (Direct Memory Access)
The memory process of transferring data directly between memory and peripheral devices without microprocessor intervention.

Expansion Slot
A large connector that allows you to connect an expansion board (add-on board) to your computer. Expansion slots provide for the addition of new features or specialized functions to your computer.

Extended Memory
System memory above 1MB that can be accessed directly by Microsoft Windows 95 and some operating systems.

Flash BIOS
A type of firmware that can be changed through the use of special software procedures. The BIOS contains basic information your computer needs to run. To protect it from accidental damage, it ran only be changed through the flashing procedure.

GB (Gigabyte)
1024MB, or 1048576KB, or 1073741824 bytes. For example; 4GB is 4096MB, or 4194304KB, or 4294967296 bytes.

Hard Drive
A large-capacity data-storage device that is installed inside the computer. Data written to the hard disk remains until it is overwritten or erased.

Hardware
The physical parts of the computer. Hardware includes everything from the screws and brackets to the chips and circuit boards.

I/O (Input/Output)
Describes the transfer of data to and from the computer - primarily between the computer and peripheral devices such as printers.

ISA (Industry Standard Architecture) Expansion Slot
An expansion slot that is designed for 8- or 16- bit ISA add-in boards. The ISA expansion bus operates at 8 MHz.

Jumper
A set of bare pins which can be connected to enable or disable a feature of the circuit board.

KB (Kilobyte)
1024 byte. For example, 8KB is shorthand for 8192 bytes.

Local Bus
A bus or data path that is directly accessible by the microprocessor.

MB (Megabyte)
1024 kilobytes or 1048576 bytes. For example, 16MB is 16384KB or 16777216 bytes.

Memory
A type of component that stores data while the computer is using it. Memory requires power to retain the data stored in it. Data stored in memory must be saved to disk before the computer is turned off or it is lost.

MHz (Megahertz)
A measure of frequency that equals a million cycles per second. The speed of the microprocessor is measured in MHz.

Ns (Nanosecond)
A measure of speed that equals a billionth of a second. The speed at which memory and other chips communicate with the system is measured in Ns.

Operating System
A low-level software package that controls the operation of the computer. The operating system includes functions that perform all of the essential tasks to run the software applications you want to use.

Parallel
A type of communication that increases the speed of data transmission by using several wires at the same time. Parallel ports can transfer a byte in the same amount of time it takes a serial port to transfer a single bit.

PCI (Peripheral Component Interconnect)
A high-speed, high-capacity standard for add-in boards (expansion boards) that identifies the data communication between the add-in board and the system board. For example, the PCI bus uses 32 data communication lines (8 or 16-bit).

PnP (Plug and Play)
A standard for add-in boards that allows you to use a new board by simply installing it in an expansion slot and then using it.

Port
A connector. Primarily used for connectors that were designed to provide communication links to your computer. For example, a serial connector is used primarily for communication and is called a port.

POST (Power-On Self-Test)
A test performed by the computer whenever you turn on the power or press the reset button. POST checks system integrity.

RAM (Random-Access Memory)
A portion of the computer system's memory that is designed as a temporary storage area for data and programs. RAM includes conventional and extended memory. You can write to and read from RAM. Information stored in RAM is erased when the system is turned off.

ROM (Read-Only Memory)
Permanent computer memory dedicated to a particular function. For example, the instructions for starting the computer when you first turn on power are contained inROM. You cannot write to ROM.

Serial Port
A type of port that provides serial communication. Serial communication sends data out, one bit at a time, down a single wire.

Socket
A connector designed for computer chips. A socket allows you to install a chip withoutsoldering it onto the printed circuit board.

USB (Universal Serial Bus)
The universal serial bus is a faster, higher-capacity replacement for the traditional serial port. It allows connections of up to 127 peripheral devices in serial configurations. Windows 98 or Memphis will include full support with all drivers.

Utility
A small program designed to help you perform a housekeeping function for thecomputer. For example, the Windows 95 to help you keep your files organized.

Write Precompensation
An old process used in hard drives to increase the power of the write process for thoseparts of the disk where the data was more spread out. Write precompensation is anobsolete process and is not used in newer drives.

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