RISC World

VirtualAcorn Tech Support

More from Aaron's tech support notebook

It's been a busy couple of months for tech support with some real head scratchers coming in. I can't claim to have solved all of these myself, so where possible I will try to include full credit to the brains behind the solution.

Power Management

There has been a long standing issue on a couple of customer's laptops. The fans on these machines would run continuously while VirtualAcorn was running, showing that the processor was working full time, even though the VirtualAcorn power management was installed. This is designed to return all unused clock cycles to Windows, or to put it more simply, VirtualAcorn only gets the CPU time/power it actually needs to do whatever it's doing at the time. If you are sitting at a machine typing into a word processor then RISC OS doesn't need much oomph to keep up with you, so you don't need to run the computer's processor flat out. Despite trying lots of things, nothing seemed to make any difference to the machines and eventually I was out of ideas.

I was then contacted by Phil Spiegelhalter, who had a laptop with exactly the same problem. Not only did he have the problem, but he also had the solution. His Laptop was usually set to "Presentation" mode, so that Windows didn't know what power saving to apply, so didn't apply any! Setting Windows to "Laptop" mode started the VirtualAcorn power management so that machine ran much cooler, for much longer.

So for anyone who has a laptop it might be worth checking the power management settings under Windows. To do this open the Windows control panel and go to the "Power Options" icon and double click on it. This will open the Power Options window, make sure you have Window correctly configured to run as a "Laptop/Portable".

In the example above the Power Scheme is set to "Home/Office Desk", this setting will allow VirtualAcorn power management to work on a desktop PC. For Laptops the correct setting should be chosen. Going back to the two customer machines in both cases the users had re-installed Windows themselves and for some reason the Power Scheme had been set the same as Phil's machine, to "Presentation" mode. Correcting this solved the power management problem for them. This brings me neatly onto my next topic, re-installing Windows.

Re-installing Windows

A lot of our tech support time seems to get taken up with customers who have re-installed Windows themselves. Doing a re-install isn't a difficult task, provided you know what you are doing, the problems arise because Windows makes it too easy for a user. Quite rightly some users assume that Windows will sort everything out for them, after all that's what it looks like it's doing. Indeed there is a lot of hand holding done by the Windows installer, unfortunately if users aren't careful they can find themselves getting hand held right down a sewer.

The Windows installer will re-install Windows for you, what it's rather unlikely to do is install other things that aren't part of Windows. If you buy a PC from a large company, such as Dell, then you will have a re-install CD for your machine that will put everything back to factory spec, normally including loading all the drivers, a PC from a smaller manufacturer, or worse still one "built by a friend who's into PC's", won't have a full re-install CD. After Windows has been installed there may still be lots missing.

Graphics Drivers

Windows will not install the drivers for your graphics card, that's something you need to do. On old versions of Windows it was obvious if the graphics card drivers hadn't been installed, your machine would be stuck in 640x480 16 colours. On WinXP that doesn't happen, instead Windows uses it's own VGA drivers that do a quite fair job in the desktop, you are quite likely to find that Windows has correctly set up the resolution and colour depth for your monitor and it will not be obvious that anything is wrong, until you start VirtualAcorn. At this point, one VirtualAcorn has been unlocked, an error message will appear on screen (typically "Unable to create back buffer") and VA won't start. Of course at this point the user comes to us, as it's our software that isn't working. Of course it's nothing to do with VirtualAcorn, it's because they haven't installed all the drivers needed.

So how can you tell if the drivers for a graphics card have been installed? It's actually very easy. Simply right click on a blank piece of the Windows backdrop and click on Properties. The Display Properties window will open. Clicking on the Settings tab will open the Display settings window. There will be a picture of a monitor. Under this will be some text, something along the lines of "Default monitor on ATI Radeon 7500". If there is nothing after the work "on" then the graphics drivers have not been installed, have a look at the examples below.

Correct graphics drivers installed

No graphics drivers installed

As you can see I've put a red ellipse around the problem area to make it more obvious. Of course graphics drivers aren't the only problem.

Other Drivers

Windows relies on a number of drivers to work correctly, the graphics drivers are simply one of them. If you need to re-install Windows then please remember that as well as installing Windows itself you will need, as a bare minimum, to also install:

  • Graphics Drivers
  • Sound Drivers
  • Network Drivers
  • Motherboard drivers (for USB etc)
  • Modem drivers
  • Drivers for any other 3rd party expansions cards
  • Drivers for any printers you have

You will need to dig through the CD's that came with the computer to make sure you have everything you need before you start. Trust me there is nothing worse than doing a re-install, then wanting to do on-line to download the latest drivers, only to find that you have mislaid the driver for your broadband modem.

Doing a Windows re-install is not difficult, but actually installing Windows itself is only half the job. VirtualAcorn will not work unless you have installed all the drivers the machine needs.

Re-naming HardDisc4

We have been asked a couple of times now about how to rename the HostFS::HardDisc4 mount. I don't recommend renaming a harddisc under RISC OS for a number of reasons. Firstly there's a high degree of probability that some things in your boot sequence simply won't use relative names.

As an example suppose there is a reference to:


In the boot sequence - if you rename the harddisc to, for example Jim, then the real path to the file would now be:


So RISC OS would no longer "find" !Printers and would throw up an error on booting.

If the entire !Boot sequence uses relative names, such as:


then renaming the harddisc shouldn't cause as many problems, although apps (and the pinboard) may still complain that they can't find things.

You can "rename" the existing HardDisc4 from the HostFS control panel by making a new HostFS mount that points to the HardDisc4 folder (as seen by Windows) with a new name (for example Jim). You would then have 2 HostFS mounts that point to the same Windows folder. Removing the one named "HardDisc4" would just leave the one called Jim, which would then become the first drive, and hence the boot drive.

Also note the mount flags for Bootable and Show DOS extensions need to be set so the new mount has the same flags as the old HardDisc4 mount.

However I really don't recommend doing this, if you really must and are prepared for the potential problems then firstly back up the file:

C:\Program Files\VirtualAcorn\VRPC-xxx\Models\Arm 7 RISC OS xxx(Jit)\Model.cfg

(where xxx is determined by your version of VirtualAcorn)

So if it all goes wrong you can put things back. Also note that if you do rename the harddisc and it does all go wrong we won't be able to provide any support and will simply tell you to put it back!

More tech support fun and games next time.


P.S. Regular readers might be interested to know that "Mr Snap" now has a cousin in Australia.