Monday, December 29, 2008

Flash memory

Flash memory is non-volatile computer memory that can be electrically erased and reprogrammed. It is a technology that is primarily used in memory cards and USB flash drives for general storage and transfer of data between computers and other digital products. It is a specific type of EEPROM (Electrically Erasable Programmable Read-Only Memory) that is erased and programmed in large blocks; in early flash the entire chip had to be erased at once. Flash memory costs far less than byte-programmable EEPROM and therefore has become the dominant technology wherever a significant amount of non-volatile, solid state storage is needed. Example applications include PDAs (personal digital assistants), laptop computers, digital audio players, digital cameras and mobile phones. It has also gained popularity in the game console market, where it is often used instead of EEPROMs or battery-powered SRAM for game save data.

Flash memory is non-volatile, which means that no power is needed to maintain the information stored in the chip. In addition, flash memory offers fast read access times (although not as fast as volatile DRAM memory used for main memory in PCs) and better kinetic shock resistance than hard disks. These characteristics explain the popularity of flash memory in portable devices. Another feature of flash memory is that when packaged in a "memory card," it is enormously durable, being able to withstand intense pressure, extremes of temperature, and even immersion in water.

Monday, December 22, 2008

486, Pentium, and Itanium

Intel introduced the 486 microprocessor in 1989, and in 1990 formally established a second design team, designing the processors code-named "P5" and "P6" in parallel and committing to a major new processor every two years, versus the four or more years such designs had previously taken. The P5 was earlier known as "Operation Bicycle" referring to the cycles of the processor. The P5 was introduced in 1993 as the Intel Pentium, substituting a trademarked name for the former part number (numbers, like 486, cannot be trademarked). The P6 followed in 1995 as the Pentium Pro and improved into the Pentium II in 1997. New architectures were developed alternately in Santa Clara, California and Hillsboro, Oregon.

The Santa Clara design team embarked in 1993 on a successor to the x86 architecture, codenamed "P7". The first attempt was dropped a year later, but quickly revived in a cooperative program with Hewlett-Packard engineers, though Intel soon took over primary design responsibility. The resulting implementation of the IA-64 64-bit architecture was the Itanium, finally introduced in June 2001. The Itanium's performance running legacy x86 code did not achieve expectations, and it failed to effectively compete with 64-bit extensions to the original x86 architecture, first from AMD (the AMD64), then from Intel itself (the Intel 64 architecture, formerly known as EM64T). As of November 2007, Intel continues to develop and deploy the Itanium.

Monday, December 15, 2008

DRAM to microprocessors

In 1983, at the dawn of the personal computer era, Intel's profits came under increased pressure from Japanese memory-chip manufacturers, and then-President Andy Grove drove the company into a focus on microprocessors. Grove described this transition in the book Only the Paranoid Survive. A key element of his plan was the notion, then considered radical, of becoming the single source for successors to the popular 8086 microprocessor.

Until then, manufacture of complex integrated circuits was not reliable enough for customers to depend on a single supplier, but Grove began producing processors in three geographically distinct factories, and ceased licensing the chip designs to competitors such as Zilog and AMD. When the PC industry boomed in the late 1980s and 1990s, Intel was one of the primary beneficiaries.

Monday, December 08, 2008

Pentium flaw

In June 1994, Intel engineers discovered a flaw in the floating-point math subsection of the Pentium microprocessor. Under certain data dependent conditions, low order bits of the result of floating-point division operations would be incorrect, an error that can quickly compound in floating-point operations to much larger errors in subsequent calculations. Intel corrected the error in a future chip revision, but nonetheless declined to disclose it

In October 1994, Dr. Thomas Nicely, Professor of Mathematics at Lynchburg College independently discovered the bug, and upon receiving no response from his inquiry to Intel, on October 30 posted a message on the Internet. Word of the bug spread quickly on the Internet and then to the industry press. Because the bug was easy to replicate by an average user (there was a sequence of numbers one could enter into the OS calculator to show the error), Intel's statements that it was minor and "not even an erratum" were not accepted by many computer users. During Thanksgiving 1994, The New York Times ran a piece by journalist John Mark off spotlighting the error. Intel changed its position and offered to replace every chip, quickly putting in place a large end-user support organization. This resulted in a $500 million charge against Intel's 1994 revenue.

Ironically, the "Pentium flaw" incident, Intel's response to it, and the surrounding media coverage propelled Intel from being a technology supplier generally unknown to most computer users to a household name. Dovetailing with an up tick in the "Intel Inside" campaign, the episode is considered by some to have been a positive event for Intel, changing some of its business practices to be more end-user focused and generating substantial public awareness, while avoiding (for most users) a lasting negative impression.