This upgrade is the Bigram from W.A.W. Electroniks, The Bigram doubles the memory of a standard CDTV, The card fits in place of the Angus (One of the square chips on the motherboard).
The Bigram CD cost 399 Dm for the basic 1 Meg version but an advanced version was also available for 599 Dm, The advanced version adds 2 Meg of fast ram plus the original 1 Meg of chip ram. The card requires no drivers to be loaded and installation would only take about five minutes, Installation can be done by anyone as long as they are carefull, All you need to do is remove the old Angus (The large square chip on the left of the CDTV, Next to the memory chips) and plug the card in its place.
The card is designed to fit around other WAW upgrades like the Bigram CD8 and Turbo CD.

Chip ram is the memory which can be used by the sound card, Graphics card and the main computer, You can have upto 2 meg of chip Ram. The CDTV has 1 meg as standard.
The Bigram was available in Germany and other countrys locally but where never available in the UK and USA. These items are quite rare (Compared to the Mini Mega chip used in the A500 & A2000).