What if the Apple ][ had run on Field-Sequential?

3 days ago

The article explores an alternate history where the Apple ][ runs on a field-sequential color system, diverging from our timeline by avoiding the Korean War, which allowed CBS's field-sequential color system to gain market share.
Field-sequential color sacrifices color depth in time rather than space, unlike composite video. The system was adopted in the US but quickly abandoned due to the Korean War's resource demands.
The alternate timeline's computer, named the Columbia ][, uses a MOS 6502 CPU and a 7MHz pixel clock, resulting in a lower resolution of 148x180 pixels compared to the Apple ][.
The Columbia ][ features unique graphics modes, including a text mode with 21x22 characters and a HIRES mode with 7 bits per byte, but lacks LORES mode due to the field-sequential system's constraints.
Color is achieved through an IRQ system that synchronizes with the 144Hz field rate, allowing for real-time edits and planar palettes, but with limited time for game logic due to the higher line rate.
The article speculates on the feasibility of other systems like the Columbia 2600 and Columbia Entertainment System in this alternate timeline, noting the challenges posed by the field-sequential color system's technical limitations.
Despite the technical challenges, the article concludes that the Columbia ][ would likely not be as successful as the Apple ][ due to the resolution limitations and the niche nature of the field-sequential color system.

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