This is RamZilla

It is the second prototype of a 2-megs interface to a coco-3.

The interface uses a Lattice CPLD for all address decoding, A9 muxing and RAS/CAS auto refreshing. It uses any pairs of 1-meg or 4-meg SIMMs, 3 or 8 or 9 chip kind, doesn't matter. Those simms in the left photo are 70ns, yes that's right! The ones below are 80ns.

See the 'scope page for timimg waveforms.

It also has outputs for adding any 4-byte chip such as a 6551 or a 6821. There are buffered lines for these extra chips and are: A0, A1, R/W, E and the four chip selects.

What it takes to install a RamZilla 2 Meg circuit board:
1. Socket IC1, the 6809E
2. Socket IC3, the 74ls245
3. Install 2 square pins to IC15, pins 13 and 11 (Hsync and Vsync)
4. Clip out and remove capacitors, C10, C11, C65 and C66, (RAS, CAS, E, Q)
That's all, and you're ready for the upgrade.