Electronic Design

Innovative Designs Use Old Technology In New Stuff

September’s Intel Developer Forum (IDF) in San Francisco was host to a plethora of partners showing off their latest stuff, including a couple of old technologies employed in new areas. One was the use of the VNC (Virtual Network Computing) protocol for accessing the BIOS interface of a remote computer. The second was the mix of SCSI and USB.

Remote BIOS Display VIA VNC

Intel introduced remote KVM (keyboard, video, mouse) support with its vPro technology for the Xeon and Core processors (see “Corporate Processors Great For Embedded Chores” at electronicdesign.com). The support is in the chipset and processor, giving users access to an embedded display via a network connection. Prior approaches required an out-of-band system with a microcontroller and network connection. Most external KVM systems were hooked into a motherboard’s keyboard, mouse, and video ports.

Intel’s Q57 an Q67 chipsets, like those on ITOX’s microATX SB330-CRM motherboard, provide the needed support (see the figure). Of course, not all Core processors have vPro support. By the way, the ITOX SB330-CRM is a nice little motherboard with an on-board TPM chip, 6-Gbit/s SATA interfaces, and EFI BIOS support.

Intel and RealVNC demonstrated how you could use a RealVNC client to control motherboards with vPro processors. RealVNC provides generic and secure VNC support. Standard VNC does not use encrypted communication, and it’s often combined with VPN or SSH tunnels. RealVNC supports the vPro encryption support.

USB Attached SCSI Protocol

USB 1.1 introduced the Bulk-Only Transport (BOT), which has been used with most USB storage devices like USB flash and hard drives. As with most USB technology at the time, it was a single command system that locked up the entire system. Even with USB 2.0, the bus speed was a match for most peripherals so there was little need for improvement.

USB 3.0 runs at 5 Gbits/s. Some peripherals like high-speed flash can fill the pipe, but efficiency would be harder to improve if BOT remained the only transfer alternative. A BOT transfer normally takes three round trips consisting of one or more USB transactions to complete.

Enter the USB Attached SCSI (UAS) Protocol (UASP), which uses SCSI commands and brings command queueing to the table. Command queueing allows asynchronous operations and is a standard part of SCSI implementations including SAS (Serial Attached SCSI) used with enterprise flash and hard-disk drives. It also provides a significant performance and efficiency boost to USB attached storage, putting it almost on par with eSATA drives. USB 3.0 has the bandwidth and the protocol to use it.

The T10 technical committee of the International Committee for Information Technology Standards (INCITS) manages the UAS standard. The USB Mass Storage Class (MSC) Working Group, which is part of the USB Implementers Forum, handles the Universal Serial Bus Mass Storage Class-USB Attached SCSI Protocol (UASP) specification. The SCSI Trade Association (SCSITA) defines the SCSI command set.

Using a common command set reduces support and compatibility issues. SATA flash and hard drives support a subset of SCSI, which is why SAS controllers can easily handle SATA and SAS drives. This also makes support of these drives via UASP significantly easier. Likewise, it means standard device drivers for operating systems like Windows and Linux work with all devices.

VIA Labs showed off its VL750 USB 3.0 to NAND flash controller, which supports UASP. The Renesas µPD720230 and PLX Technology OXU311 were examples of USB 3.0 to SATA bridge chips that support UASP. Most of these products are likely to show up in the latest USB external flash and hard drives.

UASP was designed for USB 3.0, which supports full duplex communication. It is also set up to work with USB 2.0, although at a slower rate. VNC and SCSI have been around for quite a while. It’s nice to seem them being applied in new environments. Sometimes old technology works just fine.


PLX TEchnology



USB Implementers Forum

VIA Labs

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