Rainbow Electronics AT89C51SND1C - Manual (Page 17)

17
AT8xC51SND1C
4109E–8051–06/03
Program/Code
Memory
The AT8xC51SND1C implement 64K Bytes of on-chip program/code memory.
Figure 11 shows the split of internal and external program/code memory spaces
depending on the product.
The AT83C51SND1C product provides the internal program/code memory in ROM
memory while the AT89C51SND1C product provides it in Flash memory. These 2 prod-
ucts do not allow external code memory execution.
The Flash memory increases EPROM and ROM functionality by in-circuit electrical era-
sure and programming. The high voltage needed for programming or erasing Flash cells
is generated on-chip using the standard V
DD
voltage, made possible by the internal
charge pump. Thus, the AT89C51SND1C can be programmed using only one voltage
and allows In-application software programming. Hardware programming mode is also
available using common programming tools. See the application note ‘Programming
T89C51x and AT89C51x with Device Programmers’.
The AT89C51SND1C implements an additional 4K Bytes of on-chip boot Flash memory
provided in Flash memory. This boot memory is delivered programmed with a standard
boot loader software allowing In-System Programming (ISP). It also contains some
Application Programming Interface routines named API routines allowing In Application
Programming (IAP) by using user’s own boot loader.
Figure 11. Program/Code Memory Organization
ROM Memory
Architecture As shown in Figure 11 the AT83C51SND1C ROM memory is composed of one space
detailed in the following paragraphs.
Figure 12. AT83C51SND1C Memory Architecture
4K Bytes
Boot Flash
FFFFh
F000h
0000h
64K Bytes
Code Flash
FFFFh
AT89C51SND1C
0000h
64K Bytes
Code ROM
FFFFh
AT83C51SND1C
F000h
FFFFh
64K Bytes
ROM Memory
0000h
User