1980s Vintage Computers

Home > Acorn / BBC >Archimedes A4000 > A4000 Tips

Acorn A4000 - Tips

Here are some tips for maintaining an A4000 based on my limited experience with the machine.

NiCd Battery

The A4000 was supplied with a nickel-cadmium rechargable battery soldered to the motherboard PCB. This is for a battery-backed CMOS memory chip to store configuration data. However after many years these batteries leak and can cause damage to the motherboard so much always be removed. I replaced mine with a NiMH battery.

Once replaced the configuration needs to be reset. The CMOS config is reset by pressing 'R' then powering the machine on, machine should prompt to press Break to reset CMOS. Then press and hold down Ctrl+Space, then press Break. On my machine once reset, after a power cycle the machine gave a hard drive error, then booted into the RISC desktop, showing presence of the floppy drive but no hard drive.

I followed instructions from a message on the Stardot forum for setting the configuration for the hard drive as follows. From the desktop press F12, this gives a command line at the bottom of the screen with a * prompt. Enter the following commands (followed by Return):

ADFS
DIR :4
OPT 4,2
CONFIGURE FILESYSTEM ADFS
CONFIGURE DRIVE 4
CONFIGURE BOOT

Ignore any error messages these commands may give, then press Return to exit the * command line window. Power cycle the machine and if lucky the hard drive will be recognised and the machine run whatever software was previoulsy installed. If not then please see the Stardot forum for advice.

Once the RISC OS applications are available, run the !Alarm utility to reset the date and time.

Power Supply

The A4000 power supply does not contain any Rifa capactiors, but in my example the manufacturer had used some yellow glue to hold down some components. This glue turns black and becomes conductive with age, so I took a craft knife to my power supply and carely chipped off the remaining glue, especially around thoise compoents at mains voltages. This has no effect on operation and was to save the circuitry from any future damage.

Acorn BBC Links