uiiii... never heared nor seen something of this machine.... sure, that its not a fake? Its amazing that the machine has the number 64 (like the C64 *g*) due fact of its 64k memory in its name, hehe...
Technical datas are extreme awesome for that time... But there are things i dont really may understand. The RAM is 64 and 50 K are still useable, ok....
The graphic may be 672x256 in 256 colors? Uhaa.. How should this possible with 64k total mem? Lets calulate the needed size of an 672x256 image with 8 bpls (256 colors)...
((672*256)/8) * bpls == 172032 bytes !!!
AS you see, one image with this size is uncompressed ~172 KB... Does the graphic card had own memory? If so, i dont think that the graphic card had more memory is the main memory of the machine. So i am a bit confused about this tech datas.
[Edit]
Something i found:
http://www.zock.com/8-Bit/D_Enterprise64.HTML (sadly in pure german)

Mainboard of the Enterprise 128 (with 128 KB Ram) and an extension on the left side.