Well...the attribute bus is 14 bits wide on the Inty I and II. Do we know what the specs are for the attribute format in the III? For instance, they could have widened the bus to a full 16 bits with little difficulty. So while its 2 bytes per attribute, as far as the STIC is concerned it's only one word per attribute. Similarly, they could have widened the pattern bus from 8 to 16 bits. It's already shared with the System RAM bus so the lines would already be there. It's even possible that they could have done all that and still remain within 40 pins, I would think, with some clever rearranging.
As far as the color output: it isn't a rhetorical question: how is the video getting to the Inty? Unmodified Inty I's only support external video MUX input on pin 8, whereas Inty II's also support external video replacement on pin 2.
Edited by JohnPCAE, Mon Jul 17, 2017 7:57 AM.