Rainbow Electronics AT89C5122 - 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.