RISC OS Computers: Acorn's RiscPC-II a.k.a. Phoebe
This machine, code-named Phoebe (but often mis-spelt Pheobe!), was to have been the successor to the immensely popular RiscPC, and generated a lot of interest. many existing Acorn computer users looked forward to its release with eager anticipation of owning one themselves, while others considered that its specification was too modest and being rapidly overtaken by developments elsewhere in the computer market-place.
It was a genuinely impressive beast in many ways, and despite some unavoidable limitations the finalised version was probably quite a lot better than many commentators had realised.
Whatever its potential, it never went into production, and Acorn themselves eventually shut down so that was effectively the end of any chance for Phoebe.
Projected Specification
Main Processor.
The current speed of a StrongARM from Digital is 233MHz. Digital have recently stated in the Press that the next generation StrongARM, the SA-2, is being worked upon and is expected to be released at the end of 1998.
- 1x StrongARM (rumour has it that the final StrongARM to be used in the RiscPC II will be clocked at over 400MHz) on a small card.
RAM.
EDO is the standard these days but SDRAM looks like becoming the future standard as it allows even faster data access by the processor. In any case it looks like the main RAM, probably 16MB, will be soldered to the motherboard with two extra RAM sockets available to add more.
- SDRAM support with the limit increased to 512Mbytes.
- A pseudo secondary cache of 256K is being provided, but this may be increased to 512K.
Video.
- A super fast video controller chip (VIDC20-II?) shrunk to 0.6µm.
- Maximum video resolution of 1600x1200 by 32,000 colours by 72Hz.
- 4MBytes of VRAM soldered to the main PCB.
- 200MHz video bandwidth.
Co-Processor Support.
Acorn PC card support has now been dropped. Users wishing a PC card will have to fit a PC PCI card if one is made available from a third party. Aleph Ltd is believed to be looking into this.
BUS support.
- The current RiscPC has a data bus speed of only 16MHz (32MHz in PC terminology, Acorn don't hide the true access speed), the Mk II is going to be very fast with 66MHz (@ 32bits) so the RiscPC II will straight away be well over twice the speed of an existing RiscPC (current estimates are 2-4 times faster).
- The PCI card data speed is to be 33MHz @ 32bit (throughput of 132Mbytes/sec). This is the most common speed of PCI cards available at the moment. While Intel are moving to a 66/100MHz data speed @ 64bit for PCI cards these are very expensive and are only for very specialized uses. Rumour is that the final release of the RiscPC II will have a 66MHz PCI data speed.
- Only PCI card slots will be fitted to the board but via an adaptor two existing Acorn style 'podules' can be fitted.
- PC style PCI cards will be able to be fitted to the new machine as long as third parties written the necessary driver software for each card.
Other Device Support.
- A second serial port will be available which will have at least double the existing speed of the current serial port (115Kbits/sec).
- The existing RiscPC can only support two E-IDE devices while the full E-IDE standard in the Mk II will allow up to four devices to be fitted. It will also run a lot faster than the current RiscPC IDE interface.
- A new 'PC' I/O chip which provides full Soundblaster support, 4 audio mixers, 16-bit sound sampler builtin, joysticks and MIDI.
- Full PS/2 support for keyboard and mouse as standard.
Although Acorn cancelled the RiscPC-II computer just as it was nearing completion, the striking (you either love it or hate it!) yellow cases that had been produced for its production did later become available, and a number of enthusiasts bought these and presumably fitted their existing RiscPCs' innards into them.
- Please note: all copyrighted names in the above text are fully acknowledged.
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