Registers – Rainbow Electronics AT89C5122 User Manual
Page 24
24
AT8xC5122/23
4202E–SCR–06/06
Registers
Reset Value = 0XXX X000b
Table 5. Auxiliary Register - AUXR (8Eh)
7
6
5
4
3
2
1
0
DPU
-
-
-
XRS0
EXTRAM
AO
Bit
Number
Bit
Mnemonic
Description
7
DPU
Disable weak Pull-up
0
weak pull-up is enabled
1
weak pull-up is disabled
6-3
-
Reserved
The value read from this bit is indeterminate. Do not change these bits.
2
XRS0
XRAM Size
0
256 bytes (default)
1
512 bytes
1
EXTRAM
EXTRAM bit
Cleared to access internal XRAM using MOVX @ Ri/ @ DPTR.
Set to access external memory.
Programmed by hardware after Power-up regarding Hardware Security Byte
(HSB), default setting , XRAM selected.
0
AO
ALE Output bit
Cleared , ALE is emitted at a constant rate of 1/6 the oscillator frequency (or 1/3 if
X2 mode is used)(default).
Set , ALE is active only when a MOVX or MOVC instruction is used.