I am a ZX-Spectrum fan since 1989. ZX-Spectrum platform was very popular in the USSR. In april of 1994 I got some idea how to resolve attribute clash through moving the platform from mono-system to poly-system.
The idea was to start four ZX-Spectrum-128 in parallel with small modifications of graphics data. It didn't need any changes in ROM and SOS but only total synchronization between CPUs and sharing of all control signals.
I can't say that the idea was too original one because I was inspired by the book "COMPUTER IMAGES" ("Understanding computer" Time-Life books). There I found several strings about the Pixar platform (developed by the Lucasfilm team) which processes each color component by dedicated CPU. In Zx-Poly each CPU also processes dedicated color component (R,G,B,Y). Software no so often checks information written into VRAM so that big part of games and utilities could be adapted just through edition of their graphic data.