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參數(shù)資料
| 型號： | DS87C520 |
| 英文描述： | EPROM/ROM High-Speed Micro |
| 中文描述： | EPROM/ROM高速微控制器 |
| 文件頁數(shù)： | 11/45頁 |
| 文件大小： | 1415K |
| 代理商： | DS87C520 |
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DS87C520/DS83C520 EPROM/ROM High-Speed Microcontrollers
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from 4kB to 16kB (1000h–3FFFh) is no longer located on-chip. This could result in code misalignment
and execution of an invalid instruction. The recommended method is to modify the ROMSIZE register
from a location in memory that will be internal (or external) both before and after the operation. In the
above example, the instruction which modifies the ROMSIZE register should be located below the 4kB
(1000h) boundary, so that it will be unaffected by the memory modification. The same precaution should
be applied if the internal program memory size is modified while executing from external program
memory.
Off-chip memory is accessed using the multiplexed address/data bus on P0 and the MSB address on P2.
While serving as a memory bus, these pins are not I/O ports. This convention follows the standard 8051
method of expanding on-chip memory. Off-chip ROM access also occurs if the
EA
pin is a logic 0.
EA
overrides all bit settings. The
PSEN
signal goes active (low) to serve as a chip enable or output enable
when Ports 0 and 2 fetch from external ROM.
Figure 2. ROM Memory Map
DATA MEMORY ACCESS
Unlike many 8051 derivatives, the
DS87C520/DS83C520 contain on-chip data memory. They also
contain the standard 256 bytes of RAM accessed by direct instructions. These areas are separate. The
MOVX instruction accesses the on-chip data memory. Although physically on-chip, software treats this
area as though it was located off-chip. The 1kB of SRAM is between address 0000h and 03FFh.
Access to the on-chip data RAM is optional under software control. When enabled by software, the data
SRAM is between 0000h and 03FFh. Any MOVX instruction that uses this area will go to the on-chip
RAM while enabled. MOVX addresses greater than 03FFh automatically go to external memory through
Ports 0 and 2.
ROM SIZE IGNORED
ROM SIZE ADJUSTABLE
DEFAULT = 16kB
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| DS87C520-ECL | EPROM/ROM High-Speed Micro |
| DS87C520-ENL | EPROM/ROM High-Speed Micro |
| DS87C520-MCL | EPROM/ROM High-Speed Micro |
| DS87C520-MNL | EPROM/ROM High-Speed Micro |
| DS87C520-QCL | EPROM/ROM High-Speed Micro |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| DS87C520_1 | 制造商:DALLAS 制造商全稱:Dallas Semiconductor 功能描述:EPROM/ROM High-Speed Micro |
| DS87C520+ECL | 制造商:Maxim Integrated Products 功能描述:MICRO OTP HI SPD 44TQFP 33MHZ PB-FR - Trays |
| DS87C520+MCL | 制造商:Maxim Integrated Products 功能描述:MICRO OTP HI SPD 40PDIP 33MHZ PB-FR - Rail/Tube 制造商:Maxim Integrated Products 功能描述:IC 8BIT CPU CMOS 87C520 DIP40 |
| DS87C520+MNL | 制造商:Maxim Integrated Products 功能描述:MICRO HI SPD 40PDIP 33MHZ IND PB-FR - Rail/Tube |
| DS87C520+QCL | 制造商:Maxim Integrated Products 功能描述:MCU 8BIT CISC 16KB EPROM 5V 44PLCC - Rail/Tube |
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