ZX Cube Pentagon

Implementation of the Russian Spectrum-compatible Pentagon computer, 1991 edition. Unlike the original board, it is laid out in the style of a multi-story tower of 10 by 10 cm boards. Two side faces contain the same bus for the entire computer, the lower face - an additional bus for linking specific boards, the upper face - input/output ports. It is assumed that the resulting cube will be 10x10x10 cm.