C128 256K MMU expansion

Hi

There are now two more C128s expanded to 256K of RAM using MMU expansion:
http://www.zimmers.net/anonftp/pub/cbm/documents/projects/memory/c128/1028/index.html

I have decided to make a nice daughterboard for this project, that would
fit into a C128DCR. There is not much space near MMU: between power supply,
SID and power connector, so I moved whole logic into a GAL. (My first GAL
project and they are already obsolete - I'm late to the game).

Here is the result: https://github.com/ytmytm/c128-mmu-256k-exp

In this process I also found a mistake in the documentation. The correct
information comes from the ASCII drawing of the schematic in TXT format.
The description contains a mistake in all formats. It says:

> Lead the 74LS138's pin 10 to the 4066's pin 6 and to the 74F00's
> pins 1 and 2. Lead the 74F00's pin 3 to the 4066's pin 12.

Pins 6 and 12 are swapped - instead it should be:

> Lead the 74LS138's pin 10 to the 4066's pin 12 and to the 74F00's
> pins 1 and 2. Lead the 74F00's pin 3 to the 4066's pin 6.

Pity to say I stumbled on this already in 1998, when I built my first
version (based on piggy-backed TTL chips with lots of wires) but I
neglected to write down what exactly was the issue.

ytm