Preliminary W77E516
Machine cycles in standard 8032 = 10 + (26 * CNT)
Machine cycles in W77E516 = 10 + (26 * CNT)
If CNT = 50
Clock cycles in standard 8032= ((10 + (26 *50)) * 12 = (10 + 1300) * 12 = 15720
Clock cycles in W77E516 = ((10 + (26 * 50)) * 4 = (10 + 1300) * 4 = 5240
Block Move with Two Data Pointers in W77E516:
; SH and SL are the high and low bytes of Source Address
; DH and DL are the high and low bytes of Destination Address
; CNT is the number of bytes to be moved
Machine cycles of W77E516
#
2
2
3
2
3
2
2
2
2
2
2
3
MOV
MOV
MOV
INC
MOV
LOOP:
MOVX
INC
DEC
MOVX
INC
INC
DJNZ
R2, #CNT
DPS, #00h
DPTR, #DHDL
DPS
DPTR, #SHSL
A, @DPTR
DPTR
DPS
@DPTR, A
DPTR
DPS
R2, LOOP
; Load R2 with the count value
; Clear DPS to point to DPTR
; Load DPTR with Destination address
; Set DPS to point to DPTR1
; Load DPTR1 with Source address
; Get data from Source block
; Increment source address
; Clear DPS to point to DPTR
; Write data to Destination
; Increment destination address
; Set DPS to point to DPTR1
; Check if all done
Machine cycles in W77E516 = 12 + (15 * CNT)
If CNT = 50
Clock cycles in W77E516 = (12 + (15 * 50)) * 4 = (12 + 750) * 4 = 3048
We can see that in the first program the standard 8032 takes 15720 cycles, while the W77E516 takes
only 5240 cycles for the same code. In the second program, written for the W77E516, program
execution requires only 3048 clock cycles. If the size of the block is increased then the saving is even
greater.
External Data Memory Access Timing
The timing for the MOVX instruction is another feature of the W77E516. In the standard 8032, the
MOVX instruction has a fixed execution time of 2 machine cycles. However in the W77E516, the
duration of the access can be varied by the user.
The instruction starts off as a normal op-code fetch of 4 clocks. In the next machine cycle, the
W77E516 puts out the address of the external Data Memory and the actual access occurs here. The
user can change the duration of this access time by setting the STRETCH value. The Clock Control
SFR (CKCON) has three bits that control the stretch value. These three bits are M2-0 (bits 2-0 of
CKCON). These three bits give the user 8 different access time options. The stretch can be varied
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Publication Release Date: August 16, 2002
Revision A1