[SiriusHardware]

Further to the above: I've just checked mine and I'm glad I did. The battery has started to go bad, causing localised corrosion around it. The pad on the topside around the battery -ve terminal looked especially bad, as though it had been etched out of existence entirely - fortunately, after removal of the battery, there still proved to be metal underneath a heavy layer of whatever the top layer had turned into.

Several component leads in the near-area had turned luminous malachite green, as had the four or so CPU socket pins nearest to the battery. One through-hole connection had almost rotted away and has been salvaged by passing a snug fitting piece of tinned copper wire through the hole and soldering it to the cleaned up pads on both sides.

Strangest of all, the screen printing in the immediate area has lifted from the PCB surface and just drifts away like confetti when touched, a pity as the PCB was previously in perfect cosmetic condition.

Needless to say I have now permanently removed the battery. Its original function (to retain user programs in memory during power down) has been rendered partly redundant by the facility to download code into the system through a serial interface.

Oddly enough the battery does not look bad at first inspection, it was only when I popped off the white plastic lid that I found the battery itself covered in white crystalline snow.

If you have one of these in storage, I would urge you to check it now. Mine dates from the early 1990s.