TS80C51RA2 Atmel Corporation, TS80C51RA2 Datasheet - Page 16

• Manufacturer Part Number: TS80C51RA2
• Description: High Performance 8-bit Microcontroller
• Manufacturer: Atmel Corporation

Figure 4. Internal and External Data Memory Address
16
FF(RA, RB, RC)/2FF (RD)
TS8xC51Rx2
00
256 bytes
XRAM
The stack pointer (SP) may be located anywhere in the 256 bytes RAM (lower and
upper RAM) internal data memory. The stack may not be located in the XRAM.
Table 5. Auxiliary Register
1.
EXTRAM
Symbol
MOVX @DPTR will generate either read or write signals on P3.6 (WR) and P3.7
(RD).
AO
-
User software should not write 1s to reserved bits. These bits may be used in future 8051
family products to invoke new features. In that case, the reset or inactive value of the
new bit will be 0, and its active value will be 1. The value read from a reserved bit is
indeterminate.
Address 08EH
FF
80
00
AUXR
Function
Not implemented, reserved for future use.
Disable/Enable ALE
Internal/External RAM (00H-FFH) access using MOVX @ Ri/ @ DPTR
indirect accesses
direct or indirect
EXTRAM
128 bytes
128 bytes
Reset value
accesses
Internal
Internal
AO
Upper
Lower
Ram
Ram
0
1
0
1
Operating Mode
ALE is emitted at a constant rate of 1/6 the oscillator frequency (or 1/3 if X2
mode is used)
ALE is active only during a MOVX or MOVC instruction
Operating Mode
Internal XRAM access using MOVX @ Ri/ @ DPTR
External data memory access
AUXR
-
X
FF
80
0100 (RA, RB, RC) or 0300 (RD)
direct accesses
-
X
Function
Register
Special
-
X
(1)
-
X
FFFF
0000
-
X
External
Memory
-
X
Data
EXTRAM
4188A–8051–10/02
0
AO
0