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EM78156EM 参数 Datasheet PDF下载

EM78156EM图片预览
型号: EM78156EM
PDF下载: 下载PDF文件 查看货源
内容描述: 8位微控制器与MASK ROM [8-Bit Microcontroller with MASK ROM]
分类和应用: 微控制器有原始数据的样本ROM
文件页数/大小: 48 页 / 420 K
品牌: ELAN [ ELAN MICROELECTRONICS CORP ]
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EM78156E  
8-Bit Microcontroller with MASK ROM  
4.1.3 R2 (Program Counter) & Stack  
Depending on the device type, R2 and hardware stack are 10-bit wide. The  
structure is depicted in Fig.3.  
Generating 1024×13 bits on-chip ROM addresses to the relative programming  
instruction codes. One program page is 1024 words long.  
R2 is set as all "0"s when under RESET condition.  
"JMP" instruction allows direct loading of the lower 10 program counter bits. Thus,  
"JMP" allows PC to go to any location within a page.  
"CALL" instruction loads the lower 10 bits of the PC, and then PC+1 is pushed into  
the stack. Thus, the subroutine entry address can be located anywhere within a  
page.  
"RET" ("RETL k", "RETI") instruction loads the program counter with the contents  
of the top-level stack.  
"ADD R2,A" allows the contents of ‘A’ to be added to the current PC, and the ninth  
and tenth bits of the PC are cleared.  
"MOV R2,A" allows to load an address from the "A" register to the lower 8 bits of  
the PC, and the ninth and tenth bits of the PC are cleared.  
Any instruction that writes to R2 (e.g. "ADD R2,A", "MOV R2,A", "BC R2,6",⋅⋅⋅⋅⋅) will  
cause the ninth and tenth bits (A8~A9) of the PC to be cleared. Thus, the  
computed jump is limited to the first 256 locations of a page.  
All instruction are single instruction cycle (fclk/2 or fclk/4) except for the instruction  
that would change the contents of R2. Such instruction will need one more  
instruction cycle.  
000H  
008H  
Reset Vector  
Interrupt Vector  
PC (A9 ~ A0)  
On-chip Program  
Memory  
Stack Level 1  
Stack Level 2  
Stack Level 3  
Stack Level 4  
Stack Level 5  
3FFH  
Fig. 3 Program Counter Organization  
Product Specification (V1.3) 07.29.2004  
5  
(This specification is subject to change without further notice)