---------------------------------------------------------
            
//This fragment 
              reads incoming frame from the CS8900A
            
//Call from 
              C as read_frame(UINT xdata * buf, UINT len)
            
//R6, R7 point 
              to buf and length is in R4, R5 
          
---------------------------------------------------------
RSEG	?PR?_READ_FRAME?CS8900
_READ_FRAME: 
MOV	DPL, R7			//Set 
  up data pointer
MOV	DPH, R6
LOOP:
MOV 	P1, #018H		//Take 
  CS8900A CS low, set address
CLR 	P1.3			//Take 
  CS8900A RD strobe low
NOP 				//Allow 
  for CS8900A access time
NOP 				//Each 
  NOP is 45 ns at 22.1184 MHz
NOP 	
MOV 	A, P2			//Read 
  low byte into port 2 
MOVX	@DPTR, A 	
INC 	DPTR
MOV	A, P3			//Read 
  high byte into port 3
MOVX	@DPTR, A 		
INC 	DPTR			//Advance 
  data pointer
MOV 	P1, #038H		//Take 
  RD strobe, chip select high
DJNZ	R5, LOOP		//Decrement, 
  loop again if needed
DJNZ	R4, LOOP
RET