My RiscPC


For the princely sum of ~£190, I bought myself a RiscPC from CJE Micro's.

The specification is:

RiscPC 610

The computer has since been expanded thus:



The first thing I did was remove the lid. Now, you'd expect that from me - but I have an excuse. I had hardware to add.

412 x 339, 31K
A quick look around... The right thing on the right is the power supply. Lower middle is the floppy drive. Immediately behind that is a two-slot backplane, into which the digitiser and IDE card were added (the digitiser has been replaced by the high speed serial hardware). The big old lump on the lower left is the ATAPI CD-ROM drive (24X). Behind that is the ARM710 processor card, and behind that is the 80486SXL-40 co-processor card. An the thing I have not mentioned is the 2.1Gb IDE harddisc precariously perched at the back. Oh, and there's a 515Mb harddisc under the CD-ROM drive.
The 515Mb drive and the CD-ROM are both connected to the RiscPC's IDE expansion. The 2.1Gb drive is connected to the primary IDE port on the Simtec card. The secondary IDE port has a flying ribbon lead out the back, so I can plug in stuff as required.


480 x 339, 43K
One of the really cool features of this computer is that it is a dual-processor system. There are two processor slots by default (though third party options give you up to five processor slots!), the front slot contains the ARM processor and the rear slot usually contains an 80x86 processor. In my case, I have an ARM710. It is tiny. I mean, you'll see hardware driver combo chips on motherboards that are bigger. It's less than an inch across.
Look at the picture for a comparison. The square array of soldered legs is for the 80486, which is exactly the size of all the other 80486's I've seen. So you'll be able to judge the size for yourself.


480 x 339, 38K
The machine, as supplied, was fitted with 1Mb of VRAM and 16Mb of RAM. There was an old 16Mb SIMM in the office that was faulty. So I figured I'd shove it in. One of three things would happen: it would crash, it would fail memory test, it would work. It worked. So I loaded memtest and ran some complex memory tests on the SIMM. No problems encountered. Indeed, I'd go as fas as to say that maybe the PC it originally was in was running it out of spec?
Still, an instant double in memory capacity. Can't be bad!
The RiscPC is supposed to be fairly fussy with what SIMMs work, and apparently not able to use those SIMMs with memory on both sides (you know, like the one I'm using...) but it seems fine. In fact, the problem isn't with the memory, it's in loading stuff into it. As I write this, I have two (different) web browsers loaded, a JPEG viewer, ChangeFSI, Edit, the PC software (with 8Mb for Windows to fit into), printer drivers, Internet stack, and a bunch of other things and - sadly - that entire lot would have fit in the original memory allocation. Need I say more? :-)

In the picture, you can see the ARM710 card on the upper left. Next to that is the DMA network connector (the flat white connector). Then you can see the VRAM, it is the thing that looks like a SIMM sat completely upright. Follow it towards the logical front and you'll see the original 16Mb SIMM at a 45-degree angle. Carry on and just before the power wires you'll see the latter 16Mb SIMM, also at a 45-degree angle.
In the space in front of the ARM710 card, it is the IOMD which basically takes care of loads of hardware I/O issues.


480 x 339, 30K
Back we are to the processors again. This time, from the other side so you can see it really does have a 486 in it, and it really is running a dual-processor system. It's only a bog-standard 486 with no floating point maths, but hey, most of my work is done under RISC OS. Windows is only needed for compatibility. The system is capable of running Windows9x, but I don't use it because it'd be amusing on such an old processor, and additionally Windows 3.11 has a much smaller footprint.
In front of the 80486 are the system ROMs. Unlike earlier versions of RISC OS, the system is now supplied on two really big ROMs. To the left (above, in the picture) is the DMA network connector.
The big chip on the 80486 card that isn't the processor itself is the interface logic for the processor interface. Basically, the card consists of a processor, a clock, some interface logic (damn complicated, I'm sure) and some cache RAM (probably not visible). That's it.
Much the same for the ARM710, except it doesn't need interfacing to its bus, and the cache is built-in.


The video controller is the VIDC2 which provides 16bit oversampled sound, and the ability to output all sorts of video signals with up to 16 million colours, and up to 2Mb VRAM. This won't woo many people these days, but when it was originally designed, it was a radical piece of hardware.
I can only see 16 million colours in 640x480 and 32,000 in 800x600. This isn't a fault of the VIDC, it's because I'm not using more VRAM! I have custom-designed my own screen modes, to suit both standard settings (ie, 800 by 600 for 'SVGA') and to suit my monitor.
For example:
# Modefile written by !MakeModes version 0.26 (14th December 1994)

monitor_title:Presario 1410

# 2048 x 768 (60Hz)
mode_name:2048 x 768
# End
I have many more modes. Loads of them, but I have only selected the common ones to be included in the menu, and I've bumped the refresh rates as high as I can. Why have flicker when a little extra fiddling can gain you a useful 10Hz in refresh rates? Then again, I can see a number of 'beating' fluorescent tubes - especially when out of phase with themselves - so maybe this means more to me than to a typical user?
VRAM is supplied seperately, either none (yes, it'll work with no VRAM, only slower), 1Mb, and 2Mb. Sadly there appears to be no option for 4Mb of VRAM, not even third-party. The memory not used is available for the system to use (kinda the reverse of 'PC' on-board video which pinches system RAM for video memory). So why bother with VRAM? Well, in order to use the extended graphics facilities, you'll need to set the system up to allow the VIDC to take care of its own memory. This is where the VRAM comes in. It is fast dual-port RAM so the system can access it as normal, and at the same time the VIDC can dip in as fast or slow as necessary to maintain the desired pixel rate (hence resolution/colours/refresh rate). When you are using VRAM, there is no virtually difference in responsiveness between 800x600 and 2048x768 because the VIDC is helping itself - there is no processor intervention here. With no VRAM, the processor must share its memory accesses with the VIDC.

What is very cool is the system can be gamma corrected. Mine is visually gamma'd to the environment of my bedroom at three o'clock in the morning. This is like the Matrix - it isn't something I can really explain to you, you have to be shown. Preferably showing you a monitor that has a grey-style desktop (ie, most of them) with a nice colour picture. You'll agree, it is nice grey, with a colour picture. Then I either load the gamma correction, or switch on another monitor with the gamma correction set up. You'll see it has slightly more contrast, it looks brighter but somehow darker, and my god, the first one was so red it is unreal. So on my monitor, the grey is grey. Proper grey. Not reddish grey. And the red, green, and blue are all separately corrected so it is visually perfect. Why? Not because it is necessary for my use of the machine, but because it can be done. And hell, if it can be done then it should be done. It took me all of two days to get totally used to a correct display where colours look correct. Now most PCs I look at look terrible. But Macs don't. What does that say to you? Uh-hu, me too. :-)



There are four (ARM) processors available:


There are five versions of the operating system:

[before you ask, we're up to RISC OS 5 and XScale processors - but those don't fit into a RiscPC]



512 x 384, 66K
What do I do? Well, pretty much the same stuff, only faster. :-)

The image (is a gamma-corrected for my printer driver, that why it might look a little bright) shows my usual setup. It is 1024x768, though I tend to use 800x600. I like it, and it is nice to know if I need more room I have a selection of larger modes available. Things are clear and readable (I am myopic).
You can see my QuickVoy internet toolbar. Telnet and ftp are not available, so I am off-line, though the telephone in green tells me that too (it goes red when on-line).
My most used things are down the right, pinned to the backdrop.
FYEO (For Your Eyes Only) is displaying one of the pictures of Willow from my website.
The PC card is running Windows 3.11.
The taskmanager is showing the application use of memory. I have 17Mb still free.
Loaded, but not in use, is my usual web browser - it's the little planet Earth icon.
Also there is trusty Edit, the basic file editor for which I wouldn't use ANY other system without. It's the blue pen.
Printer drivers for my DeskJet (a turbodriver - very fast printing) and my faxmodem are loaded.
All of the rectangles on the bottom left/centre are harddisc partitions/harddiscs except for :0 which is the floppy. I like partitions. :-) Don't be fooled into thinking it's the same disc. You are looking at three harddiscs on two different filing systems. One of the strengths of RISC OS is they can be individual (idefs::arabella.$, or adfs::4.$) or you just click and they all look the same.


The font manager is one of the major strengths of RISC OS, and is why it is making tracks in the set-top-box internet market. Acorn was mostly bought out by Pace (as in satellite decoders and set-top-boxes) and they bought into a great asset in the fontmanager alone. Of course, a processor that doesn't even get hot when running flat out, and a powerful operating system that fits into a few megabytes in its entirety are also benefits too. But the font manager rocks. It makes it possible to use fonts in crappy displays (like a television set!), and it provides sharp intelligent anti-aliasing. Recently (well, three or so years) the font manager has been able to fully anti-alias over a background which is... way cool. As for the rest of it, we've had it for well over a decade.

Here, chances are you can read the tiny text quite easily, despite the fact that it is a mere four pixels tall. If you were to zoom in, it would be much harder to read. That is because the anti-aliasing understands a little about how text is supposed to look...


Don't get me wrong, I'm not saying RISC OS is the OS to end all OSes. It has many flaws, like a total lack of inter-process protection. The OS positively invites me to drop to SVC mode and screw with its insides, and I can play merry hell with the memory tables with a few simple commands typed into BASIC.
Why? Because it is an OS written with a hacker mentality. It was intended for use as a multi-user OS just as much as Windows was intended to be plugged into the internet. Ie, it just wasn't.
But it shows amazing innovation. When you consider that Acorn not only designed the OS, they designed the processor, the support chipset, and the computers that they're running their OS on. It's amazing, and will never cease to spew forth shame on the American corporate giants that throw money and manpower at OS development issues and still get their asses kicked by the likes of Linux. Shame for not having proper anti-aliasing. Shame for TrueType fonts. Shame for Internet security so poor that the nmap utility rates many Windows95 boxen as "Trivial joke". Shame for the Melissa/LoveBug virus, and shame to those who still trust MicroSoft (third time lucky, eh guys?). Shame for megalithic operating systems that consume resources almost as fast as you buy them. Shame for releasing W95 without the ability to even change modes.
But most of all, extreme kudos to American Corporate Assholes for being so god damned frivolous with system resources that I can pick up a dirt-cheap 10Gb harddisc for coming on to spare change, and thanks for making big SIMMs cheap. And thanks for simply existing, so I can look at my RISC OS machine and know that for all its faults, it makes sense. And it won't try and tell me how it thinks I should run my world. And, just, thank God or Hecate or whoever for the fact that I do not need to use Office 2000 or any version of Word.

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Copyright © 2004 Richard Murray