JMicron Technology Corporation(Chinese

Chinese language

The Chinese language is a language or language family consisting of varieties which are mutually intelligible to varying degrees. Originally the indigenous languages spoken by the Han Chinese in China, it forms one of the branches of Sino-Tibetan family of languages...

: 智微科技) is a Taiwan

Taiwan

Taiwan , also known, especially in the past, as Formosa , is the largest island of the same-named island group of East Asia in the western Pacific Ocean and located off the southeastern coast of mainland China. The island forms over 99% of the current territory of the Republic of China following...

ese manufacturer of integrated circuits which mostly produces Serial ATA

Serial ATA

Serial ATA is a computer bus interface for connecting host bus adapters to mass storage devices such as hard disk drives and optical drives...

 and related controller chips.

Its chips are used by a number of companies, such as ASUS

ASUS

ASUSTeK Computer Incorporated is a multinational computer technology and consumer electronics product manufacturer headquartered in Taipei, Taiwan. Its product range includes motherboards, desktops, laptops, monitors, tablet PCs, servers and mobile phones...

, Gigabyte

Gigabyte Technology

Gigabyte Technology Co., Ltd. is a Taiwan-based manufacturer of computer hardware products best known for its motherboards. The company is publicly held and traded on the Taiwan Stock Exchange .-Company:...

, and MSI

MSI

-Computing:* Windows Installer, an installer system written by Microsoft for Windows platforms * Medium Scale Integration, a generation of integrated circuit chips which contain hundreds of transistors...

 in PC motherboards, though because of difficulties, newer MSI models have moved to using integrated Marvell

Marvell

-People:* Andrew Marvell, 17th-century English metaphysical poet* Marvell Wynne , American soccer player* Marvell Wynne , American baseball player-Businesses:* Marvell Technology Group, U.S. semiconductor company...

 controllers.

SSD Controllers

JMicron's JMF601 and JMF602 SATA flash controllers were reported to have issues with write latency, causing a stuttering problem. The performance problem was attributed to the small buffer size used in the controller. Some manufacturers tried to get around the problem by using 2 JMicron controllers and added more cache, but this increased the cost and still failed to deliver the improved performance. In June 2008, JMicron released version B of the affected controllers, which claimed to improve write latency and allow reserving more spare blocks to overcome the issue, but Anandtech's test showed that although JMF602B has twice the cache of the JMF602A controller and has less stutter, 4KB random write has 74x the latency and under 2% write speed of Western Digital VelociRaptor 300GB.

JMicron's SSD

Solid-state drive

A solid-state drive , sometimes called a solid-state disk or electronic disk, is a data storage device that uses solid-state memory to store persistent data with the intention of providing access in the same manner of a traditional block i/o hard disk drive...

 controller

Flash memory controller

A flash memory controller manages the data stored on flash memory and communicates with a computer or electronic device. Flash memory controllers can be designed for operating in low duty-cycle environments like SD cards, CompactFlash cards, or other similar media for use in digital cameras, PDAs,...

 is widely adopted by many SSD manufacturers such ASUS Eee PC

ASUS Eee PC

The Asus Eee PC is a subnotebook/netbook computer line from ASUSTeK Computer Incorporated, and a part of the Asus Eee product family. At the time of its introduction in late 2007, it was noted for its combination of a light weight, Linux operating system, solid-state drive , and relatively low cost...

, Corsair

Corsair Memory

Corsair Memory is a computer peripherals and hardware company headquartered in Fremont, California. Corsair designs and sells a range of products for computers, including high-speed DRAM modules, ATX power supplies , USB flash drives , CPU and memory cooling solutions, computer cases, solid-state...

, OCZ, and Transcend

Transcend

Transcend Information, Inc. is a Taiwanese company that manufactures and distributes of memory products headquartered in Taipei, Taiwan. Transcend's product portfolio consists of over 2,000 devices including memory modules, flash memory cards, USB flash drives, digital audio players, Portable...

. JMicron was the first company to provide an SSD controller chip to these companies, allowing them to produce reasonably priced MLC

MLC

-Technology:*Multi-level cell, a type of flash memory*Multi-Platform Language for Calculators*Multileaf collimator, a tool used for shaping radiation beams in external-beam radiotherapy.*Mobile Location Center, a network element in GSM Telephony Networks...

 SSDs. JMicron was to announce a new SSD controller with a DRAM cache in Q3 2009, but no such announcement occurred.

JMF602 would be succeeded by JMF612.

Linux Compatibility

JMicron SATA/IDE controllers are often incompatible with some boot loaders. In particular, those using GRUB

GNU GRUB

GNU GRUB is a boot loader package from the GNU Project. GRUB is the reference implementation of the Multiboot Specification, which provides a user the choice to boot one of multiple operating systems installed on a computer or select a specific kernel configuration available on a particular...

, such as Ubuntu

Ubuntu (operating system)

Ubuntu is a computer operating system based on the Debian Linux distribution and distributed as free and open source software. It is named after the Southern African philosophy of Ubuntu...

, cannot boot in some conditions (2006/08, 2.6.17). The 2.6.18 Linux kernel and JMicron controller BIOS 1.06.53 solved these incompatibilities, but may not be present in existing products, or may require re-flashing the motherboard BIOS. Other bootloaders such as the Windows NTLDR

NTLDR

NTLDR is the boot loader for all releases of Windows NT operating system up to and including Windows XP and Windows Server 2003. NTLDR is typically run from the primary hard disk drive, but it can also run from portable storage devices such as a CD-ROM, USB flash drive, or floppy disk...

 boot loader and EXTLINUX work fine. It has been fixed by the latest distros.

Security breach

According to the comprehensive analysis of Stuxnet

Stuxnet

Stuxnet is a computer worm discovered in June 2010. It initially spreads via Microsoft Windows, and targets Siemens industrial software and equipment...

 virus released by Symantec in 2011, a JMicron's digital certificate for Windows got compromised, allowing attacker to digitally sign malicious drivers, then revoked by Verisign

VeriSign

Verisign, Inc. is an American company based in Dulles, Virginia that operates a diverse array of network infrastructure, including two of the Internet's thirteen root nameservers, the authoritative registry for the .com, .net, and .name generic top-level domains and the .cc and .tv country-code...

 : "The attackers would have needed to obtain the digital certificates from someone who may have physically entered the premises of the two companies [ Realtek

Realtek

Realtek Semiconductor Corp. , a fabless IC design house situated in the Hsinchu Science Park, Hsinchu, Taiwan, was founded in October 1987, and subsequently approved as a listed company on the Taiwan Stock Exchange in 1998...

and JMicron] and stole them, as the two companies are in close physical proximity." states the report.

Products

JMicron makes products for a number of different applications, including:

• PATA-SATA translation Bridge
• USB-ATA bridge
• 1394+USB-SATA bridge
• PCI-Express-ATA bridge
• PCI Express-1394 bridge
• SATA Port Multiplier/Selector with RAID
• PCI Express-Ethernet bridge
• USB+SATA flash controller
• SSD controller

External links

• JMicron official website