No plans to change USB 1.1 in A9homeBy Chris Williams. Published: 4th Jul 2005, 14:31:59 | Permalink | Printable
Tributes paid instead to dead Italian hell raiserAdvantageSix have "no current plans to change the specification of the A9home" amid concerns over the suitability of the product's USB 1.1 ports. The hardware in the ARM9 powered computer is currently limited to a maximum transfer rate of 12MBit/s through the USB ports, which is further reduced by software overheads.
A9home users rely on these USB ports to hook up removable media, such as USB based CD and DVD drives, to their tiny computers. To give some context: DVD movie playback requires information to be constantly read from the disc at around 10MBit/s which is pushing it on USB 1.1. Ironically, the A9home's chipset offers hardware acceleration that is advantageous for DVD playback, once the data has arrived from the disc. AdvantageSix's Matt Edgar argued that "typical DVDs" require a sustained transfer rate of around 5MBit/s. He added: "However because of protocol overheads and CPU usage I suspect this could still be difficult."
USB 2.0 can offer up to 480MBit/s, which the Simtec USB software stack can support.
STD, aka AdvantageSix, also paid tribute today to Giuseppe Garibaldi, who was born on July 4th 1807. To recognise the Italian patriot, military leader and general rebel rouser, STD have liberated the price of a fully unlocked Unipod if bought in conjuction with a USB DVD drive. The Unipod is also a USB 1.1 device, although the internal data bus in legacy Acorn kit is severely limited anyway.
When asked how useful a CD or DVD drive connected via USB to a Unipod or A9home is, Matt replied, "The majority of RISC OS specific things are CD based, initially mostly for use with CDs. RISC OS data DVDs are starting to become available, and it seems sensible to support this and not restrict the audience for them by selling a CD only solution. The recent availability of CDVDBurn will hopefully encourage this further.
"Of course some DVD data discs from other platforms may have useful content in an appropriate format too."
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