The original board has either 32 kB or 64 kB of RAM built with 16 or 32 pcs of NEC µPD416D - a 16K dynamic RAM circuits. There are 8 pcs of Mostek ROMs (DIL24). The ROMs are different. See the table for more details. The board size is 253 x 125 mm. I have four pcs of this board. Two are NOS, other two are used and working. I have created full documentation of this board. Schematics were created in CAE system EdWin.

Fig. 1 - original board 09845-66527 Rev. B