"It's automatic. !EA at vcc the first 8k executes from internal ROM, 8k up executes from external. !EA..."

Naturally, it's true, but let me add little small note to this topic.

We design projects which use either MCU with On-Chip memory for small projects
(LCD, keyboard, power supply handling,... ) or ROMless MCU with external memories
for larger projects.
I agree with David. Use On-Chip memory and analyze, optimize, write in assembler
(we do it so) or use extra hardware for larger projects (optimize as well).
My simple question is: have you anybody some project with !EA constantly
connected at Vcc and program code size larger then On-Chip memory one?
How about wiring...

We have such similar case:
87C520 (16KB EPROM), 64KB external Flash, !EA constantly at Vcc.
Program starts on chip memory (service, CRC checking, flash programming...)
and then switches to external FLASH by setting ROMSIZE register to 0.
Main flash progarm can switch to service On-Chip and vice-versa
but it already re-started from address 0000H (include basic init).
It means there are two different programs essentially.

Regards
Vaclav