AT89C5131A-RDTIM Atmel, AT89C5131A-RDTIM Datasheet - Page 26

• Manufacturer Part Number: AT89C5131A-RDTIM
• Description: C5131A 32K FLASH USB VQFP64 IND, 5V
• Manufacturer: Atmel

Program/Code
Memory
External Code Memory
Access
Memory Interface
26
AT89C5131
The AT89C5131 implement 16/32 Kbytes of on-chip program/code memory. Figure 11
shows the split 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 V
age. Thus, the Flash Memory can be programmed using only one voltage and allows In-
application Software Programming commonly known as IAP. Hardware programming
mode is also available using specific programming tool.
Figure 11. Program/Code Memory Organization
Note:
The external memory interface comprises the external bus (Port 0 and Port 2) as well as
the bus control signals (PSEN, and ALE).
Figure 12 shows the structure of the external address bus. P0 carries address A7:0
while P2 carries address A15:8. Data D7:0 is multiplexed with A7:0 on P0. Table 33
describes the external memory interface signals.
If the program executes exclusively from on-chip code memory (not from external mem-
ory), beware of executing code from the upper byte of on-chip memory (3FFFh/7FFFh)
and thereby disrupting I/O Ports 0 and 2 due to external prefetch. Fetching code constant
from this location does not affect Ports 0 and 2.
FFFFh
3FFFh
4000h
0000h
AT89C5130A
External Code
48 Kbytes
16 Kbytes
Flash
FFFFh
7FFFh
8000h
0000h
AT89C5131A
External Code
32 Kbytes
32 Kbytes
Flash
4136C–USB–04/05
DD
volt-