I have recently glanced at the ICD firmware and the very beginning catched
my eye (see listing below). In the RCIF interrupt routine the RCREG is read
_twice_ (at address 0011 and 0017). This is I guess OK, if there is only
one byte in the FIFO, but wrong, if there are two characters waiting in the
queue. I didn't analyze the rest of the program, I was just wondering if
this could under certain circumstances cause communication problem with the
ICD. The very simple solution would be to replace the second MOVF RCREG,W
with XORLW D'24' instruction.

Regards,

Josef

0004            ORG     0004
0004 00FF       MOVWF   R7F
0005 0E03       SWAPF   STATUS,W
;Assuming bank 0
0006 1283       BCF     STATUS,RP0
0007 00FE       MOVWF   R7E
0008 080A       MOVF    PCLATH,W
0009 00FA       MOVWF   R7A
;Assuming page 0
000A 018A       CLRF    PCLATH
000B 1E8C       BTFSS   PIR1,RCIF
000C 2826       GOTO    L3      ;0026
000D 0804       MOVF    FSR,W
000E 00FC       MOVWF   R7C
000F 083C       MOVF    R3C,W
0010 0084       MOVWF   FSR
0011 081A       MOVF    RCREG,W
0012 3A24       XORLW   24      ;'$'
0013 1D03       BTFSS   STATUS,Z
0014 2817       GOTO    L0      ;0017
0015 153F       BSF     R3F,2
0016 2822       GOTO    L1      ;0022
0017 081A L0:   MOVF    RCREG,W
0018 0080       MOVWF   INDF
0019 0800       MOVF    INDF,W
001A 0ABC       INCF    R3C,F