In no particular order:
* Enable Chunky 8bit mode
Not difficult to do. THis would have helped games like DOOM a lot.
Low hanging fruit.
* Enhance Paula to support 16bit samples.
This would have been actually a very simple task if you still have the orignal design.
Paula fetches smaples anyhow in 16bit chunks so 16bit support would have been simple.
Low hanging fruit.
Adding more channels would have been more work.
* Add 16bit hicolor direct mode.
Enough Bandwidth was available for this mode.
Low hanging fruit.
* Blitter
Improving Blitter is very tricky.
Increasing clockrate would have been easy at the time but would bring no benefit without a clever buffering. Going for 32bit like some proposed here is quite a challange so it was not worth it at this time. Not a low hangiung fruit.
Nevertheless is was a bit dissapointing that the blitting power did not increase.
* Added fastmem 2MB to the A1200 would had made a big performance difference.
Yes, 2MB fast mem would have made the system a little more expensive but the performance change would been huge.
* The 3640 was to say it frankly "sad".
The 68040 bus interface is actually a lot easier than the 68030 interface. Having to convert to better 040 interface down to the 030 interface of the motherboard was a pain. The 68040 lost a significant part because of this. Would have been cool of the would have designed the A4000 for the new interface of the 040 and 060 CPUs...
* A line buffer to get double scan for free would have been cool.
But at that time this was not for free. Today we can do this for litttle and are doing it on the Natami for example - but at that time it would have increased cost.
I think it was a reasonable decision to build the system without it.
* Nevertheless Double modes (DoublePAL etc) could have been implemented slightly differently. The way they were implemented required a changed copperlist.
This could have been done without also - this way the AGA chipset could had been able to promote any old game the VGA. Its somewhat of a pity that they did not do it this way as this would have made running old games on VGA monitors so much easier.
All in all the AGA chipset was good.
The most missed features were certainly 8bit chunky.
16bit chunky would have been very nice and would have been simple to do also.
The original Blitter would have been perfect to support this mode.
Quite many people in the scene were surprised that AGA came without chunky support.
Cheers
Gunnar
http://www.natami.net
