... just "reserve enough area".

As I said above, if you are generous enough to give 16kB for the bootloader, I can't see why don't you give similar amount for the interrupts.

In fact, you can leave ALL the remaining space for the interrupts initially, and if the application demands more space, take from that interrupt which is shorter at that moment.

So, for (a crude) example, if your application is now roughly 16kB and the bootloader another 16kB, leave 16kB for each interrupt, even if each requires only 1kB now. So the application occupies 0-(say)3000, interrupts 4000-(say)4400, 8000-(say)8400 and the bootloader is c000 and up. Now the application turns out to be space hungry, so you take the biggest fuctions out of it and reloacate to say 7000-7fff. If the first interrupt grows way big and would occupy 4000-7xxx, you simply take those extra routines and move them to b000-bfff. You get the idea.

(but by the time Mr.Murphy makes your interrupts eat up several kilobytes of code memory, the application itself outgrows this micro by several orders of magnitude, and you'll find yourself negotiating with Lynn for a few more MBs of FLASH in your custom-built superfast '51... :-) ).

JW