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Millipede Electronic Graphics
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Cambridge House
Hargrave near Bury St Edmunds Suffolk IP29 5HP |
| Telephone: | 01284 850594 |
| Fax: | 01284 850351 |
| Web: | http://www.millipede.co.uk/ |
| Email: | info@millipede.co.uk |
There has been some speculation on the newsgroups with regard to Imago and the new XScale processor. XScale is Intel's successor to the StrongARM processor. This is a very exciting development as it promises many times the processor power and memory bandwidth of the current StrongARM.
Imago was always designed to accept new processors and an XScale module is already being developed. It will shortly be put through its paces. This will enable us to ensure that when Imago is released it is compatible with the XScale processor.
Main features:
Processor
Imago is currently based around the 233MHz revision-T StrongARM processor from Intel. Whilst the processor is soldered directly onto the motherboard, a small second-processor board may be mounted over the top. This can operate instead of, or in conjunction with, the motherboard processor. A board to support Intel's XScale architecture (next-generation StrongARM) has already been designed.
A standard processor expansion connector is also provided, primarily intended for an Acorn/Aleph One PC card.
Memory
Imago has two horizontally mounted 144-pin SO-DIMM sockets for use with industry-standard 64-bit SDRAM modules. These provide up to 512Mb of main memory on a 128-bit-wide data bus.
The memory can operate at rates of 100MHz to support PC100 SDRAM modules. Production versions are planned to run at 128MHz.
The new motherboard is fitted with 16Mb of flash memory. Typically 4Mb of this will be required by the operating system (e.g. RISC OS 4) and the remaining 12Mb will be available to the user. This is ideal for compact applications requiring a robust discless system.
Whilst the Risc PC motherboard only has 256 bytes of non-volatile memory, Imago includes 2K of EEROM memory and 512 bytes of battery-backed memory. 128 bytes of EEROM memory is also available to the user on each SDRAM module. This extra non-volatile memory permits storage of additional configuration parameters.
Video
The monitor video output is capable of resolutions up to 2048×1536 at 72Hz frame-rate. This resolution can now be achieved in all pixel depths, including 24-bit, 16 million colour modes.
Video is derived from main memory. Not only does this represent a significant cost saving, but it also permits multiple video buffers. The memory interface has been designed carefully to ensure that video DMA does not compromise processor access unduly.
The start address of video memory can be set freely, and this enables smooth scrolling and special effects. In particular, it allows hardware panning through very large images. It also allows the replay of animation sequences stored in memory.
The hardware has been designed to support the VESA DDC monitor standard. This allows the auto-detection of DDC-compliant monitors and considerably simplifies monitor configuration.
Sound
Imago offers major improvements over the Risc PC sound capabilities. The new sound functions are based around a PC SoundBlaster-compatible chip.
There are four analogue stereo input channels, plus one mono microphone input. These signals can be cabled to a podule panel. This panel may also include the game port, incorporating a MIDI I/O channel. (Note: this is not opto-isolated on-board as isolation is normally included in game port cable assemblies.)
In addition, two I2S digital input channels are available which, for instance, can be used to connect a Wavetable synthesiser. Further expansion of the sound system is possible through the sound DSP I/O channel, available on the A/V expansion bus.
Internally, Imago has stereo speaker outputs, so you can now fit a speaker in that space on the left! Use of a bridged amplifier circuit means that the power output of each channel is approximately four times that of the Risc PC; this probably won't scare the neighbours but will help in noisy environments.
IDE
Imago provides two IDE connectors, allowing up to four EIDE devices to be fitted. The new IDE hardware offers a major improvement in performance over the Risc PC. UltraDMA mode is planned up to 32Mb/s: that's about four times the speed of the fastest SCSI interface for the Risc PC.
Network
Imago features a built-in 100 Base-TX Ethernet interface, backwards-compatible with 10 Base-T.
USB
Two USB ports are fitted with type A host connectors. These ports automatically support dual-speed USB peripherals (12Mb/s and 1.5Mb/s data rates).
Serial I/O
Two serial I/O ports are provided, with a data rate of 460K/s on both ports. One port provides a RS232 interface; the second provides a full duplex RS422/R485 interface. Alternatively, when the RS232 port is not required, the second port may be configured to provide two half-duplex RS485 ports.
A connector is fitted for an IR expansion interface.
Game port
A standard 15-pin game port connector can be cabled to the motherboard to provide twin analogue joysticks and a non-opto-isolated MIDI I/O channel.
Keyboard and mouse
Imago uses an industry-standard PS/2 interface for both keyboard and mouse.
Podule expansion
Imago supports the podule backplane and retains compatibility with existing expansion cards, although faster podule expansion bus cycle times will be available.
A new horizontally-mounted decoded podule connector may be fitted, in the position currently occupied by the IDE interface connector.
Audio/video expansion bus
The audio/video expansion bus connects dedicated real-time data channels between the motherboard and podule expansion cards. This is intended for the development of cost effective, high performance audio/video systems.
The bus transfers up to four channels of real-time video data, under DMA to/from main memory. The video data are typically multiplexed to 27MHz, in YUV 4:2:2, YUVK 4:4:4:4 or RGBK 4:4:4:4 formats. The full video period is supported, allowing ancillary data streams (such as digital sound) to be communicated outside the normal active picture area. Video outputs are fully genlockable, and all video inputs can be asynchronous.
Two digital audio channels are provided on the A/V expansion bus, one being connected to the DSP port of the on-board sound chip.
The Risc PC genlock connector is retained for backwards compatibility, although this cannot be used when the A/V expansion bus is fitted.
Considerable attention has been paid in the development of the new motherboard to minimise electrical noise and susceptibility, making it easier to design into alternative cases whilst still meeting EMC compliance.
Millipede has manufactured a limited quantity of motherboards for development and demonstration purposes. A number of technical difficulties have caused the project to be delayed; it is now hoped to commence production early in 2001, depending on completion of tests on the XScale processor module.