CMOS Battery Pack

I switched on the BBC Master this morning and was again greeted by the ‘This is not a language’ error.  I’d pretty much fully expected it given that I’d already assumed the CMOS battery pack was dead.

I opened the old girl up and located the pack.  Fortunately although it had leaked it was positioned such that it hadn’t caused any damage.

I don’t know whether it’s the original pack, it’s certainly pretty old, you don’t see Vidor (‘They last about a month longer’) batteries any more.  In fact you don’t see much that’s made in Britain any more but that’s another story.

There are several easily found guides to building a new pack.  I found this one to be very good.  It explains clearly that a resistor and diode are required within the assembly to inhibit the charging circuit intended for the Lithium cells that were originally fitted, also suggesting that my pack was indeed a replacement.

Leaking Batteries

I’m learning quite quickly that there’s an impressive and very active community attached to the BBC and other Acorn models.

My wallet is also slightly concerned by the amount of mods that are available, I fear my Master will soon be sporting some interesting additions.

Hopefully aforementioned community won’t see the rather Heath Robinson replacement battery pack that I hacked together.  Short of parts to build a proper one and aware of the limited time left in this year’s Winter Warmup I’m afraid I resorted to copious amounts of insulating tape and reuse of the original resistor/diode assembly.

Quality Engineering

I include an image here for entertainment purposes only.  It works and will see me through the next few days until I can put something a little more professional together.

Of course all this diversionary stuff means I haven’t added any code to Yahtzee and I’m wondering whether subconsciously that’s kind of intentional.

Thanks also to other Retrochallenge participant Andrew Hazelden for pointing out that the formatting in the code I’d previously listed had gone awry.  This in turn led me to discover that there’s a WordPress shortcode you can wrap around code to preserve its formatting.

The original post has been duly amended.