T89C51AC2-RLTIM View Datasheet(PDF) - Atmel Corporation
Part Name
Description
MFG CO.
'T89C51AC2-RLTIM' PDF : 121 Pages View PDF
Program/Code
Memory
A/T89C51AC2
The A/T89C51AC2 implement 32 KB of on-chip program/code memory. Figure 17
shows the partitioning of internal and external program/code memory spaces depending
on the product.
The Flash memory increases EPROM and ROM functionality by in-circuit electrical era-
sure and programming. Thanks to the internal charge pump, the high voltage needed for
programming or erasing Flash cells is generated on-chip using the standard VDD volt-
age. Thus, the Flash Memory can be programmed using only one voltage and allows In-
System-Programming commonly known as ISP. Hardware programming mode is also
available using specific programming tool.
Figure 17. Program/Code Memory Organization
FFFFh
32 KB
external
memory
7FFFh
0000h
8000h
32 KB
internal
Flash
EA = 1
7FFFh
0000h
32 KB
external
memory
EA = 0
Notes:
1. If the program executes exclusively from on-chip code memory (not from external
memory), beware of executing code from the upper byte of on-chip memory (7FFFh)
and thereby disrupt I/O Ports 0 and 2 due to external prefetch. Fetching code con-
stant from this location does not affect Ports 0 and 2.
2. Default factory programmed parts come with maximum hardware protection. Execu-
tion from external memory is not possible unless the Hardware Security Byte is
reprogrammed. See Table 26.
33
4127H–8051–02/08
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