07/08/94
Computers with amnesia ?

All Acorn computers since the Master 128 have relied upon configuration 
settings being stored in a memory device which is kept powered even when 
the computer is switched off. This is usually, though incorrectly, 
referred to as CMOS RAM.

With the exception of the Master Compact, the power to maintain the 
settings (and the real time clock) comes from batteries inside the 
computer. The Master Compact used a device called an EEPROM (an 
Electrically Erasable Programmable Read-Only Memory) which did not 
require a battery, but only allows a limited number of write operations 
- where a Master Compact is failing to retain its settings this device 
may need replacing.

On most ARM based 32 bit systems the battery is a NiCad (Nickel Cadmium) 
cell, which is trickle charged whilst the computer is switched on. This 
can mean that after a machine has been unused for a very long period it 
may need to be left on for several hours to recharge the battery. These 
batteries should not need replacing.

The Master 128, Archimedes 305/310, Archimedes 440 and Archimedes 400/1 
series all use a battery pack with conventional battery cells. The 
recommended replacement interval for these batteries is annually, however 
they will often work for much longer. Even now, it is not uncommon to 
see a 305/310 still on it's original pair of batteries! If you've got one 
of these computers - when were your batteries last changed ! As with all 
devices powered by batteries you should replace them at recommended 
intervals, and avoid leaving discharged batteries in situ since corrosive 
substances may leak from the battery and damage the surrounding area.

Failing batteries can produce many strange symptoms, including incorrect 
time/date values, and the random disabling of modules/sideways ROMS as the 
locations used to hold the *UNPLUG settings vary because the battery can 
no longer consistently maintain sufficient power. This usually results in 
some quite strange errors - for example a Master 128 may start up using a 
different filing system to normal, or a RISC OS computer may fail to start 
up the desktop.

Ethernet based AUN networks

If you are getting poor performance from such a network you should check 
whether the Broadcast Loader is enabled on any Ethernet based stations. The 
Broadcast Loader should be disabled in these circumstances using 

*Unplug BroadcastLoader 

in a boot sequence.

Look it's magic!

The filetype system employed in RISC OS can be used to save memory and 
automatically load specific applications as they are required.

You do not, for example, have to have !Edit loaded all the time to be able 
to double-click on a text file. Provided that the application has been seen 
in a directory viewer before you double-click on a file which can be handled 
by that application the application will be loaded when it is needed.

There are also some ramifications of this: if a file does not have its usual 
icon, but instead has a blank square, the relevant application has not been 
located yet in a directory viewer. There are also some filetypes allocated to 
generic files (such as CSV - comma separated value) which are commonly used 
for interchanging data between various application - these should not be 
explicitly claimed by any application.