Linear Flash is a PC card

PC card

In computing, PC Card is the form factor of a peripheral interface designed for laptop computers. The PC Card standard was defined and developed by the Personal Computer Memory Card International Association which itself was created by a number of computer industry companies in the United States...

 flash memory

Flash memory

Flash memory is a non-volatile computer storage chip that can be electrically erased and reprogrammed. It was developed from EEPROM and must be erased in fairly large blocks before these can be rewritten with new data...

 format. Linear Flash requires no battery support, unlike somewhat faster SRAM

Static random access memory

Static random-access memory is a type of semiconductor memory where the word static indicates that, unlike dynamic RAM , it does not need to be periodically refreshed, as SRAM uses bistable latching circuitry to store each bit...

, and features read/write speeds much faster than similar, less expensive ATA-type cards, which include CompactFlash

CompactFlash

CompactFlash is a mass storage device format used in portable electronic devices. Most CompactFlash devices contain flash memory in a standardized enclosure. The format was first specified and produced by SanDisk in 1994...

 and Memory Stick

Memory Stick

Memory Stick is a removable flash memory card format, launched by Sony in October 1998, and is also used in general to describe the whole family of Memory Sticks...

. Like an SRAM, Linear Flash supports execute in place

Execute in place

In computer science, execute in place is a method of executing programs directly from long term storage rather than copying it into RAM. It is an extension of using shared memory to reduce the total amount of memory required....

 (XIP) applications in mobile PC and embedded equipment.

Linear Flash can also be read and written to by laptops and desktops with PC card slots, and is somewhat popular for sensitive data storage because the media is non-volatile and does not degrade over time. However, large-scale storage is impracatical using Linear Flash because of small card sizes (typically under 40 megabyte

Megabyte

The megabyte is a multiple of the unit byte for digital information storage or transmission with two different values depending on context: bytes generally for computer memory; and one million bytes generally for computer storage. The IEEE Standards Board has decided that "Mega will mean 1 000...

s) and prohibitive costs; megabyte-for-megabyte, Linear Flash cards are often dozens of times more expensive than ATA cards.

Combined with file management software, such as Flash Translation Layer (FTL) or M-Systems

M-Systems

M-Systems Ltd., was a Nasdaq-listed Israeli producer of Flash memory storage products founded in 1989 by Dov Moran and based in Kfar Sava, Israel. They were best known for developing and patenting the first flash drive, marketed in 1995 as DiskOnChip, and the first USB flash drive, marketed in...

 TrueFFS Flash File System, the Linear Flash cards provide removable disk emulation.

As PC Card

PC Card

In computing, PC Card is the form factor of a peripheral interface designed for laptop computers. The PC Card standard was defined and developed by the Personal Computer Memory Card International Association which itself was created by a number of computer industry companies in the United States...

s (was PCMCIA), Linear Flash cards should have a Card Information Structure (CIS). However, many memory cards do not have a CIS.

Linear Flash cards begin to develop bad blocks after about 100,000 read/write cycle

Instruction cycle

An instruction cycle is the basic operation cycle of a computer. It is the process by which a computer retrieves a program instruction from its memory, determines what actions the instruction requires, and carries out those actions...

s and thus are of dubious value on the second-hand market.

Usage

Linear Flash cards were also the primary method of data storage for Cisco

Cisco

Cisco may refer to:Companies:*Cisco Systems, a computer networking company* Certis CISCO, corporatised entity of the former Commercial and Industrial Security Corporation in Singapore...

 routers, Apple's Newton

Newton (platform)

The Newton platform was an early personal digital assistant and the first tablet platform developed by Apple, the second platform being iOS, used in the iPhone, iPod Touch and iPad. Development of the Newton platform started in 1987 and officially ended on February 27, 1998. Some electronic...

 MessagePad 100 series and 2000 series PDAs, for some early Magic Cap

Magic Cap

Magic Cap was an object-oriented operating system for PDAs developed by General Magic. Tony Fadell was in charge of the platform. Darin Adler was an architect....

, Pocket PC

Pocket PC

A Pocket PC is also known by Microsoft as a 'Windows Mobile Classic device'. It is a hardware specification for a handheld-sized computer, personal digital assistant , that runs the Microsoft 'Windows Mobile Classic' operating system...

 and Windows CE

Windows CE

Microsoft Windows CE is an operating system developed by Microsoft for embedded systems. Windows CE is a distinct operating system and kernel, rather than a trimmed-down version of desktop Windows...

 PDAs, musical synthesizer

Synthesizer

A synthesizer is an electronic instrument capable of producing sounds by generating electrical signals of different frequencies. These electrical signals are played through a loudspeaker or set of headphones...

s and for many telecom devices.

Manufacturers

Major makers of Linear Flash cards are Pretec, Smart and MagicRAM. Intel, which championed the adoption of the Linear Flash format, also made cards.

External links

• Intel Application Note AP-684 Understanding the Flash Translation Layer (FTL) Specification