Why Amigas never had a chunky mode ?

[grond]

Only if you have 256 colours, you don't waste precious RAM in a chunky mode. Planar never wastes even a single bit. The Amiga was designed when 256 or 512kb of RAM were very expensive. In addition the RAM wasn't fast enough to give you the required bandwidth for a chunky mode with reasonable resolution. So planar graphics was a perfectly logical choice in the mid-80s. When they eventually did AGA they probably realised that with now 256 colours they could have done a chunky mode without wasting RAM or bandwidth but they just considered it too much work and decided to do just a lazy patch job of ECS changing only the screen DMA engine. At that time they would not only have had to add chunky gfx but also 16 bit audio and a 32 bit blitter to have kept it competitive.

[grond]

You don't waste RAM, but you waste computing power and bandwidth when manipulating the display.

Did you really read what I wrote? I wrote: "Only if you have 256 colours, you don't waste precious RAM in a chunky mode."

An 8-colour chunky mode would need e.g. 640x256x1 bytes while an 8-colour planar mode takes only 640x256x3/8 bytes, i.e. in each chunky byte some of the bits would be "don't care" and thus wasted. Hence, a chunky mode would have been a waste of precious RAM unless it would have been a 256-colour chunky mode (there are 16-colour chunky modes in some PC gfx cards where each pixel takes on nibble). 256-colour modes were hardly feasible in 1985. When they eventually were, Commodore were too cheap or lazy or stupid to add them.