Fitting a Real Time Clock to a Microbee Premium

[ChickenMan]

Thanks Chesh for that, looks similar to the Silvestron one above but would work out much the same price as above but a lot of work obtaining parts, assembly, etc.

Or would a simpler solution be to use the original MC146818 RTC but instead of the 3.6v Ni-Cad battery, relace it with a 3.0v button battery. Would the 3.6v ver 3.0v make any difference or would the clock run slow ?