Версия у меня самая новая, 8.14...
Симулирую следующий код и получаю LATA = 0x50, PORTA = 0x10.
Глюк?
Код
processor 18F2550
include "P18F2550.INC"
config CP0=OFF, CP1=OFF, CP2=OFF, CPB=OFF, CPD=OFF
config WRT0=OFF, WRT1=OFF, WRT2=OFF, WRTB=OFF, WRTC=OFF, WRTD=OFF
config WRT3=OFF, EBTR3=OFF, CP3=OFF
config EBTR0=OFF, EBTR1=OFF, EBTR2=OFF, EBTRB=OFF
config DEBUG=OFF, XINST=OFF, MCLRE=ON, WDTPS=32768, IESO=OFF
config STVREN=ON, WDT=OFF, PBADEN=OFF, BOR=ON, BORV=3
config FOSC=HS, PLLDIV=2, CPUDIV=OSC1_PLL2, USBDIV=1, PWRT=ON
config FCMEN=OFF, VREGEN=OFF, LPT1OSC=OFF, CCP2MX=OFF, LVP=OFF
org 0
clrf PORTA
clrf TRISA
movlw 0xFF
movwf LATA