On 19 May 1995, Kalle Pihlajasaari said: > Just a few things that would be realy convenient on a new design : ... > A larger full width return stack, 32 deep say so one does not ... > A potential data stack (as mentioned by someone already, could be I can understand (and agree with) the desire for a data stack, but why does everybody keep saying they want a really deep return stack? I've written many PIC programs for both the 5x and the 6x/7x/8x parts. While I've often had to go through contortions to make my code work on the 5x, I have yet to need more than six of the eight levels available on the 6x/7x/8x, including some non-trivial interrupt processing. I'd really like to see some examples of PIC code that need more than eight levels. I'd personally much rather see extra transistors thrown at a data stack or a second FSR and IND (like the 17C42) than more return stack I don't need and won't use. On the other hand, since the return stack couldn't be needed in the same instruction cycle as a data stack access*, it could be turned into a combined data/return stack and made deeper. Cheers, Eric * except perhaps in the case of interrupts, but I wouldn't mind if it took one extra cycle to push the PC. Since the current 14-bit core is broken in this regard anyhow (interrupting an instruction that changes PCL will push the wrong return address), this would actually be a win if it fixed the problem.