Mode 4 screen (two bitplanes emulation)
is a software technique to emulate two bitplanes on-screen at once. The main advantage is that you don't need to take care of the background while moving sprites around. Moreover, graphics need 50% less memory space. On the other hand, main disadvantage is that you can use half of available colours for each bitplane. Also known as 'Mode 3'.
Used in games like: ZTB-Mission Genocide etc..
- DSK with the ACPC listing RUN"DEMO" to watch..