disabling the serial interrupt while sending a string of bytes is the only way I can get it to work (aside from adding a 2 mS delay after sbuf is loaded with a byte)

This is working:

Test:
	CLR	ES		; Disable serial interrupts
	mov	dptr,#Test_String
	call	OutStr          ; added this routine instead of "mov sbuf,a"
	SETB	ES		; Re-enable serial interrupts
	ret
;********************************************************************
; Send a null terminated string out serial port
;********************************************************************
OutStr:
	clr a
      movc a,@a+dptr	; get character
      jz exit		; stop if char = null
;;	mov	sbuf,a	;Load SBUF
;;	jnb	TI,$	;this line makes no difference when using interrupts
	call	OutChar
      inc dptr		; point to next char
      sjmp OutStr
exit:
	ret

Test_String:
DB	'This is a Test',0dh,0ah,0
;-----------------------------------------------------------------
OutChar:
	mov	sbuf,a	        ;Load SBUF
	jnb	TI,$		;wait for last bit to transfer
	clr	TI		;get ready for next byte	
	RET			;

 

I just don't see how this works and the interrupt way does not??
Anyone?

for the incoming data reception, I must have interrupts enabled.