SN8P2501D
8-Bit Micro-Controller
SONiX TECHNOLOGY CO., LTD Page 15 Version 1.5
2.1.3 LOOK-UP TABLE DESCRIPTION
In the ROM’s data lookup function, Y register is pointed to middle byte address (bit 8~bit 15) and Z register is pointed
to low byte address (bit 0~bit 7) of ROM. After MOVC instruction executed, the low-byte data will be stored in ACC and
high-byte data stored in R register.
Example: To look up the ROM data located “TABLE1”.
; To set lookup table1’s middle address
; To set lookup table1’s low address.
; To lookup data, R = 00H, ACC = 35H
; Increment the index address for next address.
; Z overflow (FFH 00), Y=Y+1
; To lookup data, R = 51H, ACC = 05H.
; To define a word (16 bits) data.
Note: The Y register will not increase automatically when Z register crosses boundary from 0xFF to
0x00. Therefore, user must be take care such situation to avoid look-up table errors. If Z register is
overflow, Y register must be added one. The following INC_YZ macro shows a simple method to process
Y and Z registers automatically.
Example: INC_YZ macro.
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