My question is where you would get 10-bit wide RAM and ROM for your new processor

Back in the 1980's, most DRAM chips were only one bit wide anyway, so you would just use ten of them instead of just eight.

ROM is slightly trickier. But if there was a new CPU that looked like it may drive sales, it is likely that a memory chip manufacturer would have produced a suitable EPROM/ROM...

Mark

Fair point MAK, I always forget that RAMs where usually 1-bit in the day.

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Maybe a dummy cycle reduce mode, where instructions that normally take 2 cycles take 1 cycle.

In 1980? Definitely fix the indirect jump bug so the fix makes it into the 6510.
I don't know if the 6502 could support much in the way of 16-bit instructions, but a 16-bit increment and 16-bit decrement would have been nice.