SAH-C515 SIEMENS [Siemens Semiconductor Group], SAH-C515 Datasheet - Page 32

• Manufacturer Part Number: SAH-C515
• Description: 8-Bit CMOS Microcontroller
• Manufacturer: SIEMENS [Siemens Semiconductor Group]

4.4
The C515 allows to switch off the ALE output signal. If the internal ROM is used (EA=1 and
PC
memory accesses (MOVX instructions). If EA=0, the ALE generation is always enabled and the bit
EALE has no effect.
After a hardware reset the ALE generation is enabled.
Special Function Register SYSCON (Address B1 H )
Bit
EALE
–
Note: The ALE swicth-off feature is available in C515-LM/1RM versions only. In case of the
Semiconductor Group
£
1FFF H ) and ALE is switched off by EALE=0, then, ALE will only go active during external data
B1 H
C515-LN/1RN versions, the SYSCON register is present without function.
ALE, Address Latch Enable
Bit No. MSB
7
–
Function
Enable ALE output
EALE = 0 :
EALE = 1 :
If EA=0, the ALE generation is always enabled and the bit EALE has no
effect on the ALE generation.
Reserved bits for future use, read by CPU returns undefined values.
6
–
EALE
5
ALE generation is disabled; disables ALE signal generation
during internal code memory accesses (EA=1). With EA=1,
ALE is automatically generated at MOVX instructions.
ALE generation is enabled
4
–
4-4
3
–
2
–
–
1
External Bus Interface
Reset Value : XX1XXXXX B
LSB
–
0
SYSCON
C515