Date   : Mon, 18 May 2009 16:29:24 +0100
From   : jumbos.bazzar@... (Mark Haysman)
Subject: MOS3.5/3.2 switchable modules and Y2k

> I recently purchased a couple of the switchable MOS3.5/3.2 modules from
> Retroclinic (such as the one in eBay 250424700773) for my two main Master
> 128s.
>
> Now, the notes indicate that among the patches, this may fix the Y2k 
> issues
> but the documentation isn't explicit about it.
>
> Given I could pull the Doomsday ROMs from these two Masters (which would 
> be
> useful as it'd free me a socket in each) does anyone know if the 
> switchable
> modules fix the Y2k issues completely with the Master RTC please?

Hi.

The Y2K code for both versions of the OS is patched in the same way as 
described on Andrew Benham's site 
(http://www.adsb.co.uk/bbc/bbc_master.html) like this:

The RTC stores the year as 00 to 99. If the year is between 80 and 99, then 
the MOS returns a value of 1980-1999, if the year is between 00 and 79, then 
one is added to the century to give years 2000-2079. It's done this way so 
that software that doesn't like the 21st century can have the date backed 
off to provide an unmodified MOS output.

I'll add that description to the Tech notes with the boards that go out in 
the next batch.

Also, if you need a "custom" build of the DualOS, just send me a mail, the 
main chip is just a 2Mbit Flash you can program yourself if you have the 
equipement, or I can do a replacement for you as they're all socketed (It 
needs to be removed to be reprogrammed, can't do it on the board). You can 
certainly lose things like Viewsheet, View and Edit if you don't need them 
and replace them with something more useful, or have both banks as 3.50, one 
as standard and the other with the ROMs swapped for different things.

Mark.