AT89LS52-16SC ATMEL [ATMEL Corporation], AT89LS52-16SC Datasheet - Page 10

• Manufacturer Part Number: AT89LS52-16SC
• Description: 8-bit Low-Voltage Microcontroller with 8K Bytes In-System Programmable Flash
• Manufacturer: ATMEL [ATMEL Corporation]

Table 5-4.
6. Memory Organization
6.1
6.2
10
AUXR1
–
DPS
Program Memory
Data Memory
AT89LS52
Reserved for future expansion
Data Pointer Register Select
DPS
0
1
AUXR1: Auxiliary Register 1
Address = A2H
Not Bit Addressable
Bit
Selects DPTR Registers DP0L, DP0H
Selects DPTR Registers DP1L, DP1H
MCS-51 devices have a separate address space for Program and Data Memory. Up to 64K
bytes each of external Program and Data Memory can be addressed.
If the EA pin is connected to GND, all program fetches are directed to external memory.
On the AT89LS52, if EA is connected to V
1FFFH are directed to internal memory and fetches to addresses 2000H through FFFFH are
directed to external memory.
The AT89LS52 implements 256 bytes of on-chip RAM. The upper 128 bytes occupy a parallel
address space to the Special Function Registers. This means that the upper 128 bytes have the
same addresses as the SFR space but are physically separate from SFR space.
When an instruction accesses an internal location above address 7FH, the address mode used
in the instruction specifies whether the CPU accesses the upper 128 bytes of RAM or the SFR
space. Instructions which use direct addressing access of the SFR space.
For example, the following direct addressing instruction accesses the SFR at location 0A0H
(which is P2).
Instructions that use indirect addressing access the upper 128 bytes of RAM. For example, the
following indirect addressing instruction, where R0 contains 0A0H, accesses the data byte at
address 0A0H, rather than P2 (whose address is 0A0H).
Note that stack operations are examples of indirect addressing, so the upper 128 bytes of data
RAM are available as stack space.
–
7
MOV 0A0H, #data
MOV @R0, #data
–
6
–
5
–
4
CC
–
3
, program fetches to addresses 0000H through
–
2
Reset Value = XXXXXXX0B
–
1
DPS
2601B–MICRO–03/05
0