I'm guessing it's to do with engineering costs and it was cheaper to make the video hardware in the early computers/consoles 8 bit instead of 16 bit.
8 bits has a maximum of 256 possible combinations then that is the maximum vertical resolution for the PAL video display.
As NTSC has a lower vertical resolution than PAL (480 lines compared to 576. So 576-480=96 interleaved lines = 48 non interleaved lines). We end up with a maximum of 256 lines MINUS the resolution difference (48 lines) which is 208 lines of vertical resolution. This was possibly dropped down to 200 lines of displayed video on NTSC computers and consoles as it would be virtually unnoticable and allow the CPU more time for calculations (instead of having to display video).
The whole PAL and NTSC vertical resolution issue is due to legacy support of older TVs. The initital TVs in the 50s couldn't manage much more resolution than 720x480 (NTSC) and 720x576(PAL) due to the speed of the valves and other components. The high cost of TV sets (until recently) has meant that the TV broadcast networks have stayed with low resolution broadcasts as a standard, so that they could reach the widest possible audience (after all who was going to go buy a new TV set so you the could watch one network, but possibly not another network's broadcast?).
Last edited by gizmomelb; 02 April 2006 at 14:24.